Prodrugs of thrombin inhibitors

ABSTRACT

There is provided compounds of formula I,  
     R 1 O(O)C—CH 2 —(R)Cgl-Aze-Pab-R 2    I  
     wherein R 1  and R 2  have meanings given in the description, which are usefull as prodrugs of inhibitors of trypsin-like proteases, such as thrombin, and in particular in the treatment of conditions where inhibition of thrombin is required (eg thrombosis) or as anticoagulants.

FIELD OF THE INVENTION

[0001] This invention relates to pharmaceutically usefil prodrugs ofpharmaceutically active compounds, which active compounds are, inparticular, competitive inhibitors of trpsin-like serine proteases,especially thrombin, the use of the prodrugs as medicaments,pharmaceutical compositions containing them and synthetic routes totheir production.

[0002] 1. Background

[0003] Blood coagulation is the key process involved in both haemostasis(ie the prevention of blood loss from a damaged vessel) and thrombosis(ie the formation of a blood clot in a blood vessel, sometimes leadingto vessel obstruction).

[0004] Coagulation is the result of a complex series of enzymaticreactions. One of the ultimate steps in this series of reactions is theconversion of the proenzyme prothrombin to the active enzyme thrombin.

[0005] Thrombin is known to play a central role in coagulation. Itactivates platelets, leading to platelet aggregation, convertsfibrinogen into fibrin monomers, which polymerise spontaneously intofibrin polymers, and activates factor XII, which in turn crosslinks thepolymers to form insoluble fibrin. Furthermore, thrombin activatesfactor V and factor VIII leading to a “positive feedback” generation ofthrombin from prothrombin.

[0006] By inhibiting the aggregation of platelets and the formation andcrosslinking of fibrin, effective inhibitors of thrombin would thereforebe expected to exhibit antithrombodc activity. In addition,antidhrombotic activity would be expected to be enhanced by effectiveinhibition of the positive feedback mechanism.

[0007] 2. Prior Art

[0008] The development of low molecular weight inhibitors of thrombinhas been described by Claesson in Blood Coagul. Fibrin. (1994) 5, 411.

[0009] Blomb{overscore (a)}ck et al (in J. Clin. Lab. Invest. 24, suppl.107, 59, (1969)) reported thrombin inhibitors based on the amino acidsequence situated around the cleavage site for the fibrinogen Aα chain.Of the amino acid sequences discussed, these authors suggested thetripeptide sequence Phe-Val-Arg would be the most effective inhibitor.

[0010] Low molecular weight peptide-based thrombin inhibitors havesubsequently been disclosed in, for example, U.S. Pat. No. 4,346,078;International Patent Applications WO 93/11152, WO 94/29336, WO 93/18060and WO 95/01168; and European Patent Applications 648 780, 468 231, 559046, 641 779, 185 390, 526 877, 542 525, 195 212, 362 002, 364 344, 530167, 293 881, 686 642 and 601 459.

[0011] More recently, thrombin inhibitors based on peptide derivativeshave been disclosed in European Patent Application 0 669 317 andInternational Patent Applications WO 95/23609, WO 95/35309, WO 96/25426and WO 94/29336.

[0012] In particular, the latter application discloses the peptidederivatives R^(a)OOC—CH₂—(R)Cgl-Aze-Pab-H, wherein R^(a) represents H,benzyl or C₁₋₆ alkyl.

[0013] Although these active compounds are known to exhibit significantantithrombin activity, it would be beneficial to improve theirpharmacokinetic properties both after oral and parenteraladministration. Examples of pharmacokinetic properties which it isdesirable to improve include:

[0014] (a) providing an improved absorption from the gastrointestinaltract, with a view to reducing intra- and/or inter-individualvariability in relation to the bioavailability of the active compounds;

[0015] (b) flattening the plasma concentration time profile (ie reducingthe peak/trough ratio in the plasma concentration over the dosinginterval), with a view to reducing the risk of falling outside thetherapeutic interval and the side effects caused by a concentration peakwhich is too high (eg bleeding), and those caused by one which is toolow (eg thrombus formation); and

[0016] (c) increasing the duration of action of the active compounds.

[0017] Moreover, oral and parenteral administration of active thrombininhibitors may lead to undesirable local bleeding (eg in the intestinallumen or subcutaneously) as a result of a high local concentration,

[0018] Finally, orally administered active thrombin inhibitors whichalso inhibit trypsin and other serine proteases in the gastrointestinaltract may exhibit additional side effects, including indigestion (eg iftrypsin is inhibited in the intestinal lumen).

[0019] Although certain N-benzyloxycarbonyl derivatives of theaforementioned active compounds are also disclosed as thrombininhibitors in International Patent Application WO 94/29336, that thesederivatives may be useful as prodrugs is not mentioned. In fact, WO94/29336 makes no mention of suitable prodrugs of the active compounds.

[0020] We have found that the above problems may be solved byadministering compounds according to the present invention which, whilstinactive per se, upon oral and/or parenteral administration aremetabolised in the body to form active thrombin inhibitors, includingthose mentioned above.

DISCLOSURE OF THE INVENTION

[0021] According to the invention there is provided a compound offormula I,

R¹O(O)C—CH₂—(R)Cgl-Aze-Pab-R²   I

[0022] wherein

[0023] R¹ represents -R³ or -A¹C(O)N(R⁴)R⁵ or -A¹C(O)OR⁴;

[0024] A¹ represents C₁₋₅ alkylene;

[0025] R² (which replaces one of the hydrogen atoms in the amidino unitof Pab-H) represents OH, OC(O)R⁶, C(O)OR⁷ or C(O)OCH(R⁸OC(O)R⁹;

[0026] R³ represents H, C₁₋₁₀ alkyl, or C₁₋₃ alkylphenyl (which lattergroup is optionally substituted by C₁₋₆alkyl, C₁₋₆ alkoxy, nitro orhalogen);

[0027] R⁴ and R⁵ independently represent H, C₁₋₆ alkyl, phenyl,2-naphthyl or, when R¹ represents -A¹C(O)N(R⁴)R⁵, together with thenitrogen atom to which they are attached represent pyrrolidinyl orpiperidinyl;

[0028] R⁶ represents C₁₋₁₇ alkyl, phenyl or 2-naphthyl (all of which areoptionally substituted by C₁₋₆ alkyl or halogen);

[0029] R⁷ represents 2-naphthyl, phenyl, C₁₋₃ alkylphenyl (which latterthree groups are optionally substituted by C₁₋₆ alkyl, C₁₋₆ alkoxy,nitro or halogen), or C₁₋₁₂ alkyl (which latter group is optionallysubstituted by C₁₋₆ alkoxy, C₁₋₆ acyloxy or halogen);

[0030] R⁸ represents H or C₁₋₄ alkyl; and

[0031] R⁹ represents 2-naphthyl, phenyt, C₁₋₆ alkoxy or C₁₋₈ alkyl(which latter group is optionally substituted by halogen, C₁₋₆ alkoxy orC₁₋₆ acyloxy); provided that when R¹ represents R³, R³ representsbenzyl, methyl, ethyl, n-butyl or n-hexyl and R² represents C(O)OR⁷,then R⁷ does not represent benzyl;

[0032] or a pharmaceutically-acceptable salt thereof (hereinafterreferred to as “the compounds of the invention”).

[0033] The compounds of the invention may exhibit tautomerism. Alltautomeric forms and mixtures thereof are included within the scope ofthe invention.

[0034] The compounds of the invention may also contain one or moreasymmetric carbon atoms and may therefore exhibit optical and/ordiastereoisomensm. All diastereoisomers may be separated usingconventional techniques, eg chromatography or fractionalcrystallisation. The various stereoisomers may be isolated by separationof a racemic or other mixture of the compounds using conventional, egfractional crystallisation or HPLC, techniques. Alternatively thedesired optical isomers may be made by reaction of the appropriateoptically active starting materials under conditions which will notcause racemisation or epimerisation, or by derivatisation, for examplewith a homochiral acid followed by separation of the diastereomericderivatives by conventional means (eg HPLC, chromatography over silica).All stereoisomers are included within the scope of the invention.

[0035] According to a further aspect of the invention there is providedthe use of a compound of formula I, as hereinbefore defined but withoutthe proviso, as a prodrug.

[0036] Alkyl groups which R³, R⁴, R⁵, R⁶, R⁷ and R⁹ may represent may belinear or, when there are a sufficient number of carbon atoms, bebranched, be cyclic or partially cyclic, be saturated or unsaturated, beinterrupted by oxygen and/or be substituted or terminated by OH,provided that the OH group is not attached to an sp² carbon atom or acarbon atom which is adjacent to an oxygen atom.

[0037] By “partially cyclic alkyl groups” we mean groups such as CH₂Ch.

[0038] Alkyl groups which R⁸ may represent, and R³, R⁶ and R⁷ may besubstituted by, may be linear or, when there are a sufficient number ofcarbon atoms, be branched, be saturated or unsaturated and/or beinterrupted by oxygen.

[0039] The alkyl portion of alkylphenyl groups which R³ and R⁷ mayrepresent may be linear or, when there are a sufficient number of carbonatoms, be branched and/or be saturated or unsaturated.

[0040] Alkylene groups which A¹ may represent may be linear or, whenthere are a sufficient number of carbon atoms, be branched and/or besaturated or unsaturated.

[0041] Alkoxy groups which R⁹ may represent, and R³, R⁷ and R⁹ may besubstituted by, may be linear or, when there are a sufficient number ofcarbon atoms, be branched and/or be saturated or unsaturated.

[0042] Acyloxy groups which R⁷ and R⁹ may be substituted by may belinear or, when there are a sufficient number of carbon atoms, bebranched and/or be saturated or unsaturated.

[0043] Abbreviations are listed at the end of this specification.

[0044] According to a further aspect of the invention there is provideda compound of formula I, as hereinbefore defined, with the additionalprovisos that:

[0045] (a) R¹ does not represent -A¹C(O)OR⁴;

[0046] (b) R⁴ and R⁵ do not independently represent H;

[0047] (c) R⁶ does not represent C₁₋₁₇ alkyl, when R² representsOC(O)R⁶.

[0048] According to a further aspect of the invention there is provideda compound of formula I, wherein:

[0049] (a) R¹ represents -A¹C(O)OR⁴;

[0050] (b) R⁴ and R⁵ independently represent H;

[0051] (c) R⁶ represents C₁₋₁₇ alkyl, when R² represents OC(O)R⁶.

[0052] When R¹ represents -A¹C(O)N(R⁴)R⁵, preferred compounds of theinvention include those wherein:

[0053] A¹ represents C₁₋₃ alkylene;

[0054] R⁴ represents H or C₁₋₆ alkyl;

[0055] R⁵ represents C₁₋₆ alkyl or C₄₋₆ cycloalkyl; or those wherein

[0056] R⁴ and R⁵ together represent pyrrolidinyl.

[0057] When R¹ represents -A¹C(O)OR⁴, preferred compounds of theinvention include those wherein:

[0058] A¹ represents C₁₋₅ alkylene;

[0059] R⁴ represents C₁₋₆ alkyl.

[0060] When R¹ represents R³, preferred compounds of the inventioninclude those wherein R³ represents H, C₁₋₁₀ alkyl (which latter groupmay be linear or, when there are a sufficient number of carbon atoms,may be branched and/or be partially cyclic or cyclic), or C₁₋₃alkyiphenyl (which latter groups is optionally substituted, may belinear or, when there are a sufficient number of carbon atoms, bebranched).

[0061] Preferred compounds of the invention include those wherein R²represents OH, OC(O)R⁶ (wherein, in the latter case, R⁶ representsoptionally substituted phenyl or C₁₋₁₇ allyl (which latter group may belinear or, when there are a sufficient number of carbon atoms, may bebranched, be cyclic or partially cyclic, and/or be saturated orunsaturated)), C(O)OR⁷ (wherein, in the latter case, R⁷ representsoptionally substituted phenyl, C₁₋₁₂ alkyl (which latter group isoptionally substituted, may be linear or, when there are a sufficientnumber of carbon atoms, may be branched, cyclic or partially cyclic,and/or saturated or unsaturated), or C₁₋₃ alkylphenyl (which lattergroup is optionally substituted, may be linear or, when there are asufficient number of carbon atoms, may be branched)), orC(O)OCH(R⁸)OC(O)R⁹ (wherein, in the latter case, R⁸ represents H ormethyl, and R⁹ represents phenyl, or C₁₋₈ alkyl (which latter group isoptionally substituted, may be linear or, when there are a sufficientnumber of carbon atoms, may be branched and/or cyclic or partiallycyclic)).

[0062] More preferred compounds of the invention include those wherein:

[0063] R¹ represents H, linear C₁₋₁₀ alkyl, branched C₃₋₁₀ alyl,partially cyclic C₄₋₁₀ alkyl, C₄₋₁₀ cycloalkyl, optionally substitutedlinear C₁₋₃ alkyphenyl, optionally substituted branched C₃ alkylphenyl,-A¹C(O)N(R⁴)R⁵ (wherein, in the latter case, A¹ represents C₁₋₃alkylene, and R⁴ represents H or C₁₋₃ alkyl and R⁵ represents C₂₋₆ alkylor C₅₋₆ cycloallyl, or R⁴ and R⁵ together represent pyrrolidinyl), or-A¹C(O)OR⁴ (wherein, in the latter case, A¹ represents C₁₋₅ alkylene andR⁴ represents C₁₋₄ alkyl);

[0064] R² represents OH, OC(O)R⁶ (wherein, in the latter case, R⁶represents optionally substituted phenyl, linear C₁₋₄ alkyl, branchedC₃₋₄ alkyl or cis-oleyl), C(O)OR⁷ (wherein, in the latter case, R⁷represents optionally substituted and/or optionally unsaturated linearC₁₋₄ alkyl or optionally substituted and/or optionally unsaturatedbranched C₃₋₄ alkyl, optionally substituted phenyl, or optionallysubstituted linear C₁₋₃ alkylphenyl or optionally substituted branchedC₃ alkylphenyl) or C(O)OCH(R⁸)OC(O)R⁹ (wherein, in the latter case, R⁸represents H or methyl and R⁹ represents phenyl, C₅₋₇ cycloalkyl, linearC₁₋₆ alkyl, branched C₃₋₆ alkyl or partially cyclic C₇₋₈ alkyl).

[0065] Particularly preferred compounds of the invention include thosewherein:

[0066] R¹ represents linear C₁₋₆ alkyl, C₆₋₁₀ cycloalkyl, or optionallysubstituted linear C₁₋₃ alkylphenyl;

[0067] R² represents OH, OC(O)R⁶ (wherein, in the latter case, R⁶represents linear C₁₋₃ alkyl or branched C₃ alkyl), C(O)OR⁷ (wherein, inthe latter case, R⁷ represents optionally substituted linear C₁₋₄ alkylor optionally substituted branched C₃₋₄ alkyl, optionally substitutedlinear C₁₋₃ alkylphenyl or branched C₃ alkylphenyl) or C(O)OCH(R₈OC(O)R⁹(wherein, in the latter case, R⁸ represents H and R⁹ represents C₅₋₇cycloalkyl, linear C₁₋₆ alkyl or partially cyclic C₇₋₈alkyl).

[0068] When R¹ represents R³ and R³ represents optionally substitutedC₁₋₃ alkylphenyl, preferred optional substituent include C₁₋₆ alkyl(especially methyl).

[0069] When R² represents C(O)OR⁷ and R⁷ represents optionallysubstituted C₁₋₁₂ alkyl, preferred optional substituents include halogen(especially chloro) and C₁₋₆ alkoxy (especially methoxy).

[0070] When R² represents C(O)OR⁷ and R⁷ represents optionallysubstituted phenyl, preferred optional substituents include C₁₋₆ alkyl(especially methyl), C₁₋₆ alkoxy (especially methoxy) and halogen(especially chloro).

[0071] When R² represents C(O)OR⁷ and R⁷ represents optionallysubstituted C₁₋₃ alkylphenyl, preferred optional substituents includenitro.

[0072] Preferred compounds of the inventon include the compounds ofExamples 1 to 68.

[0073] More preferred compounds of the invention include:

[0074] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂;

[0075] nPrOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂;

[0076] tBuOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂;

[0077] EtOOCCH₂—(R)Cgl-Aze-Pab-COOEt;

[0078] EtOOCCH₂—(R)Cgl-Aze-Pab-COO-nBu;

[0079] PrlC(O)CH₂CH₂CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0080] ChNHC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0081] (nPr)₂NC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃;

[0082] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃;

[0083] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH(CH₃)OOCCH₃;

[0084] MeOOCCH₂—(R)Cgl-Aze-Pab-OOCPh;

[0085] MeOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0086] EtOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0087] BnOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0088] nPrOOCCH₂—(R)Cgl-Aze-Pab-Z;

[0089] nPrOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0090] iPrOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0091] tBuOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0092] (nPr)₂NCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-OH;

[0093] ChNHCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-OH;

[0094] EtOOCCH₂—(R)Cgl-Aze-Pab-OAc;

[0095] HOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0096] HOOCCH₂—(R)Cgl-Aze-Pab-O-cis-Oleyl;

[0097] Cyclooctyl-OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0098] tBuCH₂OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0099] (2-Me)BnOOCCH₂—(R)Cgl-Aze-Pab-Z;

[0100] ChCH₂OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0101] ChOOCCH₂—(R)Cgl-Aze-Pab-Z;

[0102] PhC(Me)₂OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0103] (Me)₂CHC(Me)₂OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0104] BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe);

[0105] ChCH₂OOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe);

[0106] (2-Me)BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe);

[0107] EtOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-Me);

[0108] BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-Me);

[0109] BnOOCCH₂—(R)Cgl-Aze-Pab-COO-nBu;

[0110] iPrOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂;

[0111] EtOOCCH₂—(R)Cgl-Aze-Pab-COO-iBu;

[0112] BnOOCCH₂—(R)Cgl-Aze-Pab-COO-nPr;

[0113] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCCh;

[0114] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCCH₂Ch;

[0115] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH(Me)OOCPh;

[0116] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCPh;

[0117] BnOOCCH₂—(R)Cgl-Aze-Pab-COOCH(Me)OAc;

[0118] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OAc;

[0119] tBuOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OAc;

[0120] MeOOC—C(═CHEt)CH₂—OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0121] Men-OOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe); and

[0122] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CCl₃.

[0123] Particularly preferred compounds of the invention include:

[0124] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CCl₃;

[0125] BnOOCCH₂—(R)Cgl-Aze-Pab-COOnBu;

[0126] nPrOOCCH₂—(R)Cgl-Aze-Pab-Z;

[0127] Cyclooctyl-OOCCH₂—(R)Cgl-Aze-Pab-Z;

[0128] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCCh;

[0129] MeOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0130] EtOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0131] nPrOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0132] iPrOOCCH₂—(R)Cgl-Aze-Pab-OH;

[0133] BnOOCCH₂—(R)Cgl-Aze-Pab-OH; and

[0134] EtOOCCH₂—(R)Cgl-Aze-Pab-OAc.

[0135] Preparation

[0136] According to the invention there is also provided a process forthe preparation of compounds of formula I which comprises:

[0137] (a) Preparation of a compound of formula I wherein R² representsOH by reaction of a corresponding compound of formula I, wherein R²represents OC(O)R⁶ and R⁶ is as hereinbefore defined, with an alkoxidebase (eg an alkali metal alkoxide), for example at room temperature inthe presence of an appropriate organic solvent (eg THF).

[0138] (b) Preparation of a compound of formula I wherein R² representsOH by reaction of a corresponding compound of formula I wherein R²represents C(O)OR⁷ and R⁷ is as hereinbefore defined with hydroxylamine,or an acid addition salt thereof, for example at room temperature in thepresence of a suitable base (eg potassium carbonate or triethylamine)and an appropriate organic solvent (eg THF or EtOH).

[0139] (c) Preparation of a compound of formula I by reaction of acorresponding compound of formula II,

H—(R)Cgl-Aze-Pab-R²   II

[0140] wherein R² is as hereinbefore defined with a compound of formulaIII,

R¹O(O)C—CH₂—L¹   III

[0141] wherein L¹ represents a leaving group, for example halide (egbromide) or alkylsulphonate (eg trifluoromethylsulphonate) and R¹ is ashereinbefore defined, for example between room and elevated temperature(eg 40° C.) in the presence of a suitable base (eg potassium carbonate)and an appropriate organic solvent (eg THF, DMF or acetonitrile).

[0142] (d) Preparation of a compound of formula I wherein R¹ representsH and R² represents OH or C(O)OR⁷ and R⁷ is as hereinbefore defined byreaction of a corresponding compound of formula I wherein R¹ representsC₁₋₁₀ alkyl or C₁₋₃ alkylphenyl, and R² represents OH or C(O)OR⁷, with asuitable base (eg an alkali metal alkoxide or hydroxide), for example atroom temperature in the presence of an appropriate organic solvent (egwater or MeOH).

[0143] (e) Preparation of a compound of formula I wherein R² representsOC(O)R⁶ and R⁶ is as hereinbefore defined, by reaction of acorresponding compound of formula I wherein R² represents OH, with acompound of formula IV,

R⁶C(O)—O—C(O)R⁶   IV

[0144] or a compound of formula V,

R⁶C(O)Hal   V

[0145] wherein Hal represents Cl or Br and, in both cases, R⁶ is ashereinbefore defined, for example at room temperature in the presence ofa suitable base (eg triethylamine, pyridine or DMAP) and an appropriateorganic solvent (eg methylene chloride or THF).

[0146] (f) Preparation of a compound of formula I wherein R¹ representsH and R² represents OC(O)R⁶, and R⁶ is as hereinbefore defined, byreaction of a corresponding compound of formula VI

P¹O(O)C—CH₂—(R)Cgl-Aze-Pab-R²   VI

[0147] wherein P¹ represents an acid labile ester protecting group (egtBu or Bn), and R² represents OC(O)R⁶, wherein R⁶ is as hereinbeforedefined, with a suitable acid (eg TFA), for example at room temperaturein the presence of an appropriate organic solvent (eg methylenechloride).

[0148] (g) Preparation of a compound of formula I wherein R¹ representsR³, R³ represents C₁₋₁₀ alkyl or C₁₋₃ alkylphenyl, R² represents OH orC(O)OR⁷, and R⁷ is as hereinbefore defined, by a transesterification ofa corresponding compound of formula VII,

R^(1a)O(O)C—CH₂—(R)Cgl-Aze-Pab-R²   VII

[0149] wherein R^(1a) represents a C₁₋₁₀ alkyl or C₁₋₃ alkylphenyl groupother than that being formed and R² is as hereinbefore defined or analternative labile alkyl substituent, under conditions which are wellknown to those skilled in the art.

[0150] Compounds of formula II may be prepared by deprotection of acompound of formula VII,

Boc-(R)Cgl-Aze-PabR²   VIII

[0151] wherein R² is as hereinbefore defined, under conditions which arewell known to those skilled in the art.

[0152] Compounds of formula VI and VII may be prepared analogously tothose methods described hereinbefore for preparation of compounds offormula I, in which R¹ represents R³ and R³ represents C₁₋₁₀ alkyl orC₁₋₃ alkylphenyl.

[0153] Compounds of formula VIII may be prepared by reaction of acompound of formula IX,

H-Pab-R²   IX

[0154] wherein R² is as hereinbefore defined with Boc-Cgl-Aze-OH, forexample at room temperature in the presence of a suitable couplingsystem (eg EDC), an appropriate base (eg DMAP) and a suitable organicsolvent (eg dichloromethane or acetonitrile).

[0155] Compounds of formula VIII, wherein R² represents OH may beprepared by reaction of a corresponding compound of formula VIII,wherein R² represents C(O)OR⁷ or C(O)OCH(R⁸)OC(O)R⁹, with hydroxylamine,or an acid addition salt thereof, for example at room temperature in thepresence of a suitable base (eg potassium carbonate or triethylamine)and an appropriate organic solvent (eg THF or EtOH).

[0156] Compounds of formula VIII, wherein R² represents C(O)OR⁷ orC(O)OCH(R⁸)OC(O)R⁹, may be prepared by reaction of Boc-(R)Cgl-Aze-Pab-Hwith a compound of formula X,

L²C(O)OR^(2a)   X

[0157] wherein L² represents a leaving group (eg halogen or phenolate)and R^(2a) represents R⁷ or —CH(R⁸OC(O)R⁹ and R⁷, R⁸ and R⁹ are ashereinbefore defined, for example at or below room temperature in thepresence of a suitable base (eg NaOH) and an appropriate organic solvent(eg THF).

[0158] Compounds of formula VIII, wherein R² represents OC(O)R⁶ mayalternatively be prepared by reaction of a corresponding compound offormula VIII, wherein R² represents OH with a compound of formula IV ashereinbefore defined or a compound of formula V as hereinbefore defined,for example at room temperature in the presence of a suitable base (egtriethylamine, pyridine or DMAP) and an appropriate organic solvent (egmethylene chloride or THF).

[0159] Compounds of formula VIII wherein R² represents OC(O)R⁶ mayalternatively be prepared by reaction of Boc-(R)Cgl-Aze-Pab-H with acompound of formula XI,

R⁶C(O)—O—O—C(O)R⁶   XI

[0160] wherein R⁶ is as hereinbefore defined, for example at roomtemperature in the presence of an appropriate organic solvent (eg THF).

[0161] Compounds of formula VIII wherein R² represents OH may beprepared by reaction of a corresponding compound of formula VIII,wherein R² represents OC(O)R⁶ and R⁶ is as hereinbefore defined with asuitable base (eg an alkali metal alkoxide), for example at roomtemperature in the presence of an appropriate solvent (eg THF).

[0162] Compounds of formula IX are well known in the literature or maybe prepared using methods analogous to those described hereinbefore. Forexample, compounds of formula IX wherein R² represents C(O)OR⁷ orC(O)OCH(R⁸)OC(O)R⁹ and R⁷, R⁸ and R⁹ are as hereinbefore defined may beprepared by reaction of H-Pab-H, or a protected derivative thereof, witha compound of formula X, as hereinbefore defined, for example at orbelow room temperature in the presence of a suitable base (eg NaOH) andan appropriate organic solvent (eg THF).

[0163] Boc-(R)Cgl-Aze-Pab-H may be prepared by reaction of H-Pab-H, or aprotected derivative thereof, with Boc-Cgl-Aze-OH, for example asdescribed hereinbefore for compounds of formula VIII.

[0164] Boc-(R)Cgl-Aze-Pab-H may alternatively be prepared bydeprotection of a compound of formula XII,

Boc-(R)Cgl-Aze-Pab-P²   XII

[0165] wherein P² represents a protecting group orthogonal to Boc, underconditions which are well known to those skilled in the art.

[0166] Compounds of formula III, IV, V, X, XI and XII are eithercommercially available, are well known in the literature, or areavailable using known techniques (eg as described hereinafter).

[0167] The compounds of the invention may be isolated from theirreaction mixtures using conventional techniques.

[0168] It will be appreciated by those skilled in the art that in theprocess described above the functional groups of intermediate compoundsmay need to be protected by protecting groups.

[0169] Functional groups which it is desirable to protect includehydroxy, amino, anidino and carboxylic acid. Suitable protecting groupsfor hydroxy include trialkylsilyl and diarylsilyl groups (egt-butyldimethylsilyl, t-butyldiphenylsilyl or trimethylsilyl) andtetrahydropyranyl. Suitable protecting groups for carboxylic acidinclude C₁₋₆ alkyl or benzyl esters. Suitable protecting groups foramino and amidino include t-butyloxycarbonyl or benzoyloxy carbonyl.Amidino nitrogens may be either mono or diprotected.

[0170] Protecting groups may be removed in accordance with techniqueswhich are well known to those skilled in the art, such as thosedescribed hereinafter.

[0171] The use of protecting groups is fully described in ‘ProtectiveGroups in Organic Chemistry’, edited by J W F McOmie, Plenum Press(1973), and ‘Protective Groups in Organic Synthesis’, 2nd edition, T WGreene & P G M Wutz, Wiley-Interscience (1991).

[0172] Medical and Pharmaceutical Use

[0173] The compounds of the invention are useful because they aremetabolised in the body to form compounds which possess pharnmacologicalactivity. They are therefore indicated as pharmaceuticals and inparticular as prodrugs.

[0174] In particular, the compounds of the invention, although they areinactive to thrombin per se, are metabolised in the body to form potentinhibitors of thrombin, for example as demonstrated in the testdescribed below.

[0175] By “the compounds of the invention are inactive to thrombin perse” we mean that they exhibit an IC₅₀TT value, as determined in Test Abelow, of greater than 1 μM.

[0176] The compounds of the invention are thus expected to be useful inthose conditions where inhibition of thrombin is required.

[0177] The compounds of the invention are thus indicated both in thetherapeutic and/or prophylactic treatment of thrombosis andhypercoagulability in blood and tissues of animals including man.

[0178] It is known that hypercoagulability may lead to thromboembolicdiseases.

[0179] Thrombo-embolic diseases which may be mentioned include activatedprotein C resistance, such as the factor V-mutation (factor V Leiden),and inherited or acquired deficiencies in antithrombin mfi, protein C,protein S, heparin cofactor II. Other conditions known to be associatedwith hypercoagulability and thrombo-embolic disease include circulatingantiphospholipid antibodies (Lupus anticoagulant), homocysteinemi,heparin induced thrombocytopenia and defects in fibrinolysis. Thecompounds of the invention are thus indicated both in the therapeuticand/or prophylactic treatment of these conditions.

[0180] The compounds of the invention are further indicated in thetreatment of conditions where there is an undesirable excess of thrombinwithout signs of hypercoagulability, for example in neurodegenerativediseases such as Alzheimer's disease.

[0181] Particular disease states which may be mentioned include thetherapeutic and/or prophylactic treatment of venous thrombosis andpulmonary embolism, arterial thrombosis (eg in myocardial infarction,unstable angina, thrombosis-based stroke and peripheral arterialthrombosis) and systemic embolism usually from the atrium duringarterial fibrillation or from the left ventricle after transmuralmyocardial infarction.

[0182] Moreover, the compounds of the invention are expected to haveutility in prophylaxis of re-occlusion (ie thrombosis) afterthrombolysis, percutaneous trans-luminal angioplasty (PTA) and coronarybypass operations; the prevention of re-thrombosis after microsurgeryand vascular surgery in general.

[0183] Further indications include the therapeutic and/or prophylactictreatment of disseminated intravascular coagulation caused by bacteria,multiple trauma, intoxication or any other mechanism; anticoagulanttreatment when blood is in contact with foreign surfaces in the bodysuch as vascular grafts, vascular stents, vascular catheters, mechanicaland biological prosthetic valves or any other medical device; andanticoagulant treatment when blood is in contact with medical devicesoutside the body such as during cardiovascular surgery using aheart-lung machine or in haemodialysis.

[0184] In addition to its effects on the coagulation process, thrombinis known to activate a large number of cells (such as neutrophils,fibroblasts, endothelial cells and smooth muscle cells). Therefore, thecompounds of the invention may also be useful for the therapeutic and/orprophylactic treatment of idiopathic and adult respiratory distresssyndrome, pulmonary fibrosis following treatment with radiation orchemotherapy, septic shock, septicemia, inflammatory responses, whichinclude, but are not limited to, edema, acute or chronic atherosclerosissuch as coronary arterial disease, cerebral arterial disease, peripheralarterial disease, reperfusion damage, and restenosis after percutaneoustrans-luminal angioplasty (PTA).

[0185] Compounds of the invention that inhibit trypsin and/or thrombinmay also be useful in the treatment of pancreatitis.

[0186] According to a further aspect of the present invention, there isprovided a method of treatment of a condition where inhibition ofthrombin is required which method comprises administration of atherapeutically effective amount of a compound of formula I as definedabove, or a pharmaceutically acceptable salt thereof, to a personsuffering from, or susceptible to such a condition.

[0187] The compounds of the invention will normally be administeredorally, buccally, rectally, dermally, nasally, tracheally, bronchially,by any other parenteral route or via inhalation, in the form ofpharmaceutical preparations comprising the prodrug either as a freebase, or a pharmaceutical acceptable non-toxic organic or inorganic acidaddition salt, in a pharmaceutically acceptable dosage form. Dependingupon the disorder and patient to be treated and the route ofadministration, the compositions may be administered at varying doses.

[0188] The compounds of the invention may also be combined and/orco-administered with any antithrombotic agent with a different mechanismof action, such as the antiplatelet agents acetylsalicylic acid,ticlopidine, clopidogrel, thromboxane receptor and/or synthetaseinhibitors, fibrinogen receptor antagonists, prostacyclin mimetics andphosphodiesterase inhibitors and ADP-receptor (P₂T) antagonists.

[0189] The compounds of the invention may further be combined and/orco-administered with thrombolytics such as tissue plasminogen activator(natural or recombinant), streptokinase, urokinase, prourokinase,anisolated streptokinase plasminogen activator complex (ASPAC), animalsalivary gland plasminogen activators, and the like, in the treatment ofthrombotic diseases, in particular myocardial infarction.

[0190] According to a further aspect of the invention there is thusprovided a pharmaceutical formulation including a compound of formula Ias hereinbefore defined, or a pharmaceutically acceptable salt thereof,in admixture with a pharmaceutically acceptable adjuvant, diluent orcarrier.

[0191] Suitable daily doses of the compounds of the invention intherapeutical treatment of humans are about 0.001-100 mg/kg body weightat peroral administration and 0.001-50 mg/kg body weight at parenteraladministration.

[0192] The compounds of the invention have the advantage that they mayhave improved pharmacokdnetic properties, such as those identifiedhereinbefore, both after oral and parenteral administration, whencompared with compounds of formula:

R^(a)O(O)C—CH₂—(R)Cgl-Aze-Pab-H

[0193] wherein R^(a) is as hereinbefore defined, and in particular thecompound wherein R^(a) represents H.

[0194] The compounds of the invention are inactive to thrombin, trypsinand other serine proteases. The compounds thus remain inactive in thegastrointestinal tract and the potential complications experienced byorally administered anticoagulants which are active per se, such asbleeding and indigestion resulting from inhibition of trypsin, may thusbe avoided.

[0195] Furthermore, local bleeding associated with and after parenteraladministration of an active thrombin inhibitor may be avoided by usingthe compounds of the invention.

[0196] The compounds of the invention may also have the advantage thatthey may be more efficacious than, be less toxic than, be longer actingthan, have a broader range of activity than, produce fewer side effectsthan, be more easily absorbed than, or that they may have other usefulpharmacological properties over, compounds known in the prior art.

[0197] Biological Tests

[0198] Test A

[0199] Determination of Thrombin Clotting Time (TT)

[0200] Human thrombin (T 6769, Sigma Chem Co, final concentration of 1.4NIH units/mL) in buffer solution, pH 7.4, 100 μL, and inhibitorsolution, 100 μL, were incubated for one min. Pooled normal citratedhuman plasma, 100 μL, was then added and the clotting time measured inan automatic device (KC 10, Amelung).

[0201] The clotting time in seconds was plotted against the inhibitorconcentration, and the IC₅₀TT was determined by interpolation.

[0202] IC₅₀TT is the concentration of inhibitor that doubles thethrombin clotting time for human plasma.

[0203] Test B

[0204] Determination of Thrombin Time in Plasma Ex Vivo

[0205] The inhibition of thrombin after oral or parenteraladministration of the compounds of the invention were examined inconscious rats which, one or two days prior to the experiment, wereequipped with a catheter for blood sampling from the carotid artery. Onthe experimental day, the compound, dissolved in ethanol:Solutol™:water(5:5:90), was administered and blood samples were withdrawn at fixedtimes into plastic tubes containing 1 part sodium citrate solution (0.13mol per L.) and 9 parts of blood. The tubes were centrifuged to obtainplatelet poor plasma. The plasma was used for determination of thrombintime as described below.

[0206] The citrated rat plasma, 100 μL, was diluted with a salinesolution, 0.9%, 100 μL, and plasma coagulation was started by theaddition of human thrombin (T 6769, Sigma Chem Co, USA) in a buffersolution, pH 7.4, 100 μL. The clotting time was measured in an automaticdevice (KC 10, Amelumg, Germany).

[0207] The concentrations of the active thrombin inhibitorHO(O)C—CH₂(R)Cgl-Aze-Pab-H (see International Patent Application WO94/29336) in the rat plasma were estimated by the use of standard curvesrelating the thrombin time in the pooled citrated rat plasma to knownconcentrations of the aforementioned active thrombin inhibitor dissolvedin saline.

[0208] Based on the estimated plasma concentrations of the activethrombin inhibitor HO(O)C—CH₂(R)Cgl-Aze-Pab-H (which assumes thatthrombin time prolongation is caused by the aforementioned compound) inthe rat, the area under the curve after oral and/or parenteraladministration of the prodrug was calculated (AUCpd) using thetrapezoidal rule and extrapolation of data to infinity.

[0209] The bioavailability of the active thrombin inhibitorHO(O)C—CH₂(R)Cgl-Aze-Pab-H after oral or parenteral administration ofthe prodrug was calculated as below:

[0210] [(AUCpd/dose)/(AUCactive,iv/dose]×100

[0211] where AUCactive,iv represents the AUC obtained after intravenousadministration of HO(O)C—CH₂(R)Cgl-Aze-Pab-H to conscious rats asdescribed above.

[0212] Test C

[0213] Determination of Thrombin Time in Urine Ex Vivo

[0214] The amount of the active thrombin inhibitorHO(O)C—CH₂(R)Cgl-Aze-Pab-H that was excreted in urine after oral orparenteral administration of the compounds of the invention, dissolvedin ethanol:Solutol™:water (5:5:90), was estimated by determination ofthe thrombin time in urine ex vivo (assuming that thrombin timeprolongation is caused by the aforementioned compound).

[0215] Conscious rats were placed in metabolism cages, allowing separatecollection of urine and faeces, for 24 hours following oraladministration of compounds of the invention. The thrombin time wasdetermined on the collected urine as described below.

[0216] Pooled normal citrated human plasma (100 μL) was incubated withthe concentrated rat urine, or saline dilutions thereof, for one minute.Plasma coagulation was then initiated by the administration of humanthrombin (T 6769, Sigma Chem Company) in buffer solution (pH 7.4; 100μL). The clotting time was measured in an automatic device (KC 10;Amelung).

[0217] The concentrations of the active thrombin inhibitorHO(O)C—CH₂(R)Cgl-Aze-Pab-H in the rat urine were estimated by the use ofstandard curves relating the thrombin time in the pooled normal citratedhuman plasma to known concentrations of the aforementioned activethrombin inhibitor dissolved in concentrated rat urine (or salinedilutions thereof). By multiplying the total rat urine production overthe 24 hour period with the estimated mean concentration of theaforementioned active inhibitor in the urine, the amount of the activeinhibitor excreted in the urine (AMOUNTpd) could be calculated.

[0218] The bioavailability of the active thrombin inhibitorHO(O)C—CH₂(R)Cgl-Aze-Pab-H after oral or parenteral administration ofthe prodrug was calculated as below:

[(AMOUNTpd/dose)/(AMOUNTactive,iv/dose]×100

[0219] where AMOUNTactive,iv represents the amount excreted in the urineafter intravenous administration of HO(O)C—CH₂(R)Cgl-Aze-Pab-H toconscious rats as described above.

[0220] Test D

[0221] Determination of HO(O)C—CH₂—(R)Cgl-Aze-Pab-H in urine by LC-MS

[0222] The amount of the active thrombin inhibitorHO(O)C—CH₂—(R)Cgl-Aze-Pab-H that was excreted in urine after oral orparenteral administration of the compounds of the invention, dissolvedin ethanol:Solutol™:water (5:5:90), was measured by LC-MS analysis asdescribed below.

[0223] The animal studies were performed as described in Method C above.Urine samples were collected and frozen at −20° C. before they wereanalysed.

[0224] Urine samples were analysed for their content ofHO(O)C—CH₂—(R)Cgl-Aze-Pab-H according to the following method:

[0225] Thawed urine samples were mixed and, if required, spineed in acentrifuge. Solid phase extraction tubes (Analytichem Bond Elut. No.1210-2059) were activated with 1.0 mL of methanol and conditioned with1.0 mL of acetonitrile:water (50:50), followed by 1.0 mL of 0.1% formicacid. 50 μL of the working internal standard (20 μmol/L) was added toeach extraction tube. For urine standards, 50 μL of standard solutionwas added. 200 μL of a sample or, for urine standards, blank urine wasadded to each tube and thereafter pulled through via gravity or a gentlevacuum. Residual urine was washed out with 1.0 mL of ammonium acetate (2mmol/L), before elution with 1.0 mL of acetonitrile:ammonium acetate (2mmol/L) (35:65). The collected eluate was transferred to autosamplervials. 30 μL of the extract was injected onto the LC column (HypersilBDS-C18; 3 μm; 75 mm×4.0 mm i.d.; Hewlett-Packard No. 79926 03-354),eluted with ammonium acetate buffer (1.3 mmol/L) with 40% acetonitrileand 0.1% formic acid at 0.75 mL/min. The effluent was split so that 30μL/min entered the electrospray ion source of a P-E Sciex API-3 massspectrometer. HO(O)C—CH₂—(R)Cgl-Aze-Pab-H andHO(O)C—CH₂—(R)Cgl-Pro-Pab-H (internal standard) both have retentiontimes near 1.5 minutes. Their molecular ions ((M+H)⁺) were monitored atm/z 430.2 and 444.2 respectively, at unit mass resolution. Urinestandards at two levels, one being at the limit of quantification, wereused for calibration based on peak area ratios ofHO(O)C—CH₂—(R)Cgl-Aze-Pab-H over the internal standard. Linearity of themethod was checked over the range 0.050-20 μmol/L. The coefficient ofvariation was 1-2% at 1-20 μmol/L and 7% at 0.50 μmol/L. The limit ofquantification was 0.050 μmol/L.

[0226] By multiplying the total urine production over the 24 hour periodby the measured concentration of HO(O)C—CH₂—(R)Cgl-Aze-Pab-H in theurine, the amount of the active inhibitor excreted in urine (AMOUNTpd)could be calculated. The bioavailability of the active thrombininhibitor was then calculated as described in Method C above.

[0227] The invention is illustrated by way of the following examples.

EXAMPLES

[0228] General Experimental Procedures

[0229] Mass spectra were recorded on a Finnigan MAT TSQ 700 triplequadrupole mass spectrometer equipped with an electrospray interface.

[0230] The ¹H NMR and ¹³C NMR measurements were performed on BRUKER ACP300 and Varian UNITY plus 400 and 500 spectrometers, operating at ¹Hfrequencies of 300.13, 399.96 and 499.82 MHz respectively, and at ¹³Cfrequencies of 75.46, 100.58 and 125.69 MHz respectively. Chemicalshifts are reported in δ units.

[0231] Preparation of Starting Materials

[0232] Boc-(R)Cgl-Aze-Pab-H, Boc-(R)Cgl-Aze-Pab×HCl, H—(R)Aze-Pab-Z,H—(R)Aze-Pab-Z×HCl, Bn-OOCCH₂—(R)Cgl-Aze-Pab-Z, Boc-(R)Cgl-Aze-Pab-Z,Boc-(R)Cgl-Aze-OH and Pab-Z×HCl were prepared according to the methodsdescribed in International Patent Application WO 94/29336.

Example 1

[0233] EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂

[0234] (i) Boc-(R)Cgl-Aze-Pab-COOCH₂CH═CH₂

[0235] To a solution of Boc-(R)Cgl-Aze-Pab-H (6.1 g; 13 mmol) in THF(125 mL) and 2M NaOH (70 mL; 140 mmol) at 0° C. was added dropwise allylchloroformate (1.7 g; 14 mmol). After stirring at 0° C. for 1 h, thereaction was mixture concentrated, water was added (100 mL) and theresulting aqueous phase was extracted with methylene chloride (3×100mL). The combined organic phases were concentrated to give 6.4 g of acrude product which was purified by flash chromatography usingEtOAc:THF:Et₃N (68:29:3) as eluent. Concentration gave 5.8 g (81%) ofthe subtitle compound as a white solid.

[0236]¹H NMR (500 MHz, CDCl₃): δ 8.19 (bt, 1H), 7.78 (d, 2H), 7.26 (d,2H), 6.02 -5.92 (m, 1H), 5.32 (d, J=17 Hz, 1H), 5.18 (d, J=10 Hz, 1H),5.06 (d, J=7 Hz, 1H), 4.82 (bs, 1H), 4.61 (d, J=6 Hz, 2H), 4.58-4.48 (m,1H), 4.38-4.27 (m, 2H), 4.14-4.03 (m, 1H), 3.77-3.68 (m, 1H), 2.60-0.90(m, 24H).

[0237]¹³C NMR (125 MHz, CDCl₃) carbonyl and amidine signals: δ 172.70,170.74, 168.02, 164.54, 155.98.

[0238] (ii) H—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂×2TFA

[0239] To a solution of Boc-(R)Cgl-Aze-Pab-COOCH₂CH═CH₂ (2.03 g; 3.65mmol; from step (i) above) in methylene chloride (15 mL) at 0° C. wasadded TFA (15 mL). The reaction mixture was stirred at ambienttemperature for 3 h followed by concentration to give the 2.8 g of thesubtitle compound as a white solid.

[0240]¹H NMR (500 MHz, MeOH (d4)): δ 7.80 (d, 2H), 7.57 (d, 2H), 6.02(m, 1H), 5.45 (d, J=17 Hz, 1H), 5.33 (d, J=10 Hz, 1H), 5.91-4.80 (m,3H), 4.56 (s, 2H), 4.38 (bq, J=8 Hz, 1H), 3.71 (d, J=7 Hz, 1H),2.76-2.60 (m, 1H), 2.35-2.20 (m, 1H), 1.9-1.0 (m, 11H).

[0241] (iii) EtOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂

[0242] A mixture of H—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂×2TFA (649 mg; 0.95mmol; from step (ii) above), K₂CO₃ (656 mg, 4.8 mmol), water (0.1 mL),and THF (10 mL) was stirred at 40° C. for 2 h followed by addition ofethyl bromoacetate (190 mg; 1.14 mmol) in THF (1 mL). After stirring at40° C. for 4 h and at ambient temperature for 14 h the reaction mixturewas filtered, concentrated, and purified by flash chromatography usingEtOAc:THF:Et₃N (68:29:3) as eluent to give 244 mg (47%) of the titlecompound as a white solid.

[0243]¹H NMR (400 MHz, CDCl₃): δ 8.46 (t, 1H), 7.81 (d, 2H), 7.35 (d,2H), 6.08-5.94 (m, 1H), 5.35 (d, J=18 Hz, 1H), 5.23 (d, J=11 Hz, 1H),4.93 (dd, J=6 and 9 Hz, 1H), 4.66 (d, 2H), 4.62-4.38 (AB part of anABX-spectrum), 4.16-4.04) (m, 4 H), 3.20 (d, 2H), 2.86 (d, 1H),2.64-2.45 (m, 2H), 2.0-1.0 (m 17H).

[0244]¹³C NMR (100 MHz, CDCl₃) carbonyl and amidine signals: δ 175.33,172.24, 170.72, 168.19, 164.35.

Example 2 nPrOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂

[0245] The title compound was prepared according to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂×2TFA (503mg; 0.74 mmol; see Example 1 (ii) above) and n-propyl bromoacetate (160mg, 0.88 mmol) to give 277 mg (68%) as a white solid.

[0246]¹H-NMR (400 MHz, CDCl₃): δ 8.48 (bt, 1H), 7.83 (d, 2H), 7.35 (d,2H), 6.76 (broad, 1H), 6.02 (m, 1H), 5.37 (dd, 1H), 5.24 (dd, 1H), 4.94(t, 1H), 4.67 (dd, 2H), 4.49 (AB part of an ABX-spectrum, 2H), 4.12 (m,2H), 3.98 (t, 2H), 3.24 (AB-system, 2H), 2.87 (d, 1H), 2.52 (m, 2H),1.99 (bd, 2H), 1.80-1.50 (m, 7H), 1.61 (q, 2H), 1.30-1.10 (m, 2H), 1.00(qd, 2H), 0.90 (t, 3H).

[0247]¹³C-NMR (100 MHz, CDCl₃) amidine and carbonyl signals: δ 175.4,172.3, 170.7, 167.9, 164.5

Example 3 tBuOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂

[0248] The title compound was prepared according to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂×2TFA (285mg; 0.42 mmol; see Example 1(ii) above) and t-butyl bromoacetate (96 mg;0.50 mmol) to give 93 mg (39%) as a white solid.

[0249]¹H NMR (500 MHz, CDCl₃): δ 8.50 (bt, 1H), 7.81 (d, 2H), 7.36 (d,2H), 6.07-5.97 (m, 1H), 5.36 (d, J=16 Hz, 1H), 5.22 (d, J=10 Hz, 1H),4.93 (dd, J=9 and 6 Hz, 1H), 4.76 (d, J=6 Hz, 2H), 4.57-4.46 (m, 2H),4.18-4.04 (m, 2H), 3.19-3.08 (AB-spectrum, J_(AB)=20 Hz, 2H), 2.86 (d,J=8 Hz, 1H), 2.72-2.53 (m, 2H), 2.0-0.9 (m, 23H).

[0250]¹³C NMR (100 MHz, CDCl₃) amidine and carbonyl signals: δ 175.28,171.53, 170.76, 167.81, 164.1.

Example 4 EtOOCCH₂—(R)Cgl-Aze-Pab-COOEt

[0251] (i) Boc-(R)Cgl-Aze-Pab-COOEt

[0252] The sub-title compound was prepared according the proceduredescribed in Example 1(i) from Boc-(R)Cgl-Aze-Pab-H (600 mg; 1.3 mmol)and ethyl chloroformate (150 mg; 1.4 mmol) yielding 240 mg (34%) as awhite solid.

[0253]¹H-NMR (300 MHz, CDCl₃): δ 9.37 (bs, 1H), 8.16 (bs, 1H), 7.72 (d,2H), 7.18 (d, 2H), 5.17 (d, 1H), 4.73 (t, 1H), 4.47 (dd, 1H), 4.27 (m,2H), 4.06 (q, 2H), 3.66 (t, 1H), 2.48 (m, 1H), 2.37 (m, 1H), 1.4-1.8 (m,7H), 1.22 (s, 9H), 1.3-0.8 (m, 7H).

[0254]¹³C-NMR (75MHz, CDCl₃) carbonyl and amidine signals: δ 172.6,170.7, 167.9, 164.8, 156.0

[0255] (ii) H-(R)Cgl-Aze-Pab-COOEt×2HCl

[0256] To a solution of Boc-(R)Cgl-Aze-Pab-COOEt (240 mg; 0.44 mmol;from step (i) above) in EtOAc (20 mL) was added hydrogen chloride at 0°C. over 5 minutes. The reaction mixture was stirred at 0° C. for 1 hfollowed by concentration to give 225 mg (100%) as a white solid.

[0257]¹H-NMR (300 MHz, D₂O): δ 7.85 (d, 2H), 7.61 (d, 2H), 4.98 (dd,1H), 4.60 (s, 1H), 4.44 (p, 5H), 3.90 (d, 1H), 2.73 (m, 1H), 2.37 (m,1H), 2.0-1.65 (m, 9H), 1.39 (t, 3H), 1.4-1.1 (m, 7H), 0.98 (m, 1H).

[0258]¹³C-NMR (75 MHz, D₂O) amidine and carbonyl signals: δ 172.7,169.4, 166.8, 154.3.

[0259] (iii) EtOOCCH₂—(R)Cgl-Aze-Pab-COOEt

[0260] The title compound was prepared according to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOEt×2HCl (160 mg;0.31 mmol; from step (ii) above) and ethyl bromoacetate (52.5 mg; 0.31mmol). Yield: 100 mg (61%) as a light yellow powder.

[0261]¹H-NMR (300 MHz, CDCl₃): δ 8.48 ( bt, 1H), 7.81 (d, 2H), 7.38 (d,2H), 4.51 (AB part of an ABX-spectrum, 2H), 4.21 (q, 2H), 4.15-4.05 (m,4H), 3.21 (AB-spectrum, 2H), 2.86 (d, 1H), 2.68 (m, 1H), 2.53 (m, 1H),1.96 (bd, 2H), 1.90-1.70 (m, 12H), 1.35 (t, 3H), 1.22 (t, 6H), 1.30-0.95(m, 2H).

[0262]¹³C-NMR (75 MHz, CDCl₃) carbonyl and amidine signals: δ 175.5,172.2, 170.7, 167.6, 164.9

Example 5 EtOOCCH₂—(R)Cgl-Aze-Pab-COO-nPr

[0263] (i) Boc-(R)Cgl-Aze-Pab-COO-nPr

[0264] The sub-title compound was prepared according to the proceduredescribed in Example 1(i) above using Boc-(R)Cgl-Aze-Pab-H (6.0 g; 13mmol;) and n-propyl chloroformate (1.57 mL; 14 mmol). Yield 5.4 g (76%).

[0265]¹H-NMR (400 MHz, CDCl₃): δ 8.25 (bt, 1H), 7.82 (d, 2H), 7.31 (d,2H), 5.09 (bd, 1H), 4.87 (dd, 1H), 4.58 (dd, 1H), 4.39 (dd, 2H), 4.14(q, 1H), 4.10 (t, 2H), 3.79 (t, 1H), 2.54 (dm, 2H), 2.21 (s, 1H),1.87-1.55 (m, 8H), 1.33 (s, 9H), 1.45-1.0 (m, 4H), 0.99 (t, 3H).

[0266]¹³C-NMR (100 MHz, CDCl₃) amidine and carbonyl signals: δ 172.7,170.6, 167.8, 165.0, 155.9.

[0267] (ii) H—(R)Cgl-Aze-Pab-COO-nPr×2TFA

[0268] The sub-title compound was prepared according to the proceduredescribed in Example 1(ii) using 2.1 g (3.7 mmol) ofBoc-(R)Cgl-Aze-Pab-COO-nPr (from step (i) above). Yield 3.7 g.

[0269]¹H-NMR (400 MHz, MeOH-d₄): δ 7.77 (d, 2H), 7.60 (d, 1H), 4.86 (dd,1H), 4.56 (AB part of an ABX-spectrum, 2H), 4.33 (m, 4H), 3.72 (d, 1H),3.30 (m, 1H), 2.68 (m, 1H), 2.28 (m, 1H), 1.9-1.7 (m, 9H), 1.4-1.1 (m,6H), 1.02 (t, 3H).

[0270]¹³C-NMR (100 MHz, MeOH-d₄) carbonyl and amidine signals: δ 172.7,169.3, 168.0, 161.4.

[0271] (iii) EtOOCCH₂—(R)Cgl-Aze-Pab-COO-nPr

[0272] The title compound was prepared according to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-nPr×2TFA (472 mg;0.69 mmol; from step (ii) above) and ethyl bromoacetate (138 mg; 0.83mmol) to give 0.22 mg (58%) as a white solid.

[0273]¹H-NMR (400 MHz, CDCl₃): δ 8.46 (bt, 1H), 7.82 (d, 2H), 7.32 (d,2H), s 4.92 (dd, 1H), 4.49 (AB part of an ABX-spectrum, 2H), 4.10 (m,6H), 3.23 (AB-spectrum, 2H), 2.80 (dm, 2H), 1.98 (bd, 2H),1.74 (q, 2H),1.63 (dd, 2H), 1.52 (m, 1), 1.21 (t, 3H), 1.201.10 (m, 2H), 0.98 (t,3H).

[0274]¹³C-NMR (100 MHz, CDCl₃) carbonyl and amidine signals: δ 175.3,172.2, 170.7, 167.6, 164.8.

Example 6 MeOOCCH₂—(R)Cgl-Aze-Pab-COO-nPr

[0275] The title compound was prepared according to the proceduredescribed in Example 1 (iii) above from H—(R)Cgl-Aze-Pab-COO-nPr×2TFA(365 mg; 0.53 mmol; see Example 5(ii) above) and methyl bromoacetate (98mg; 0.64 mmol) to give 114 mg (41%) as a white solid.

[0276]¹H-NMR (500 MHz, CDCl₃): δ 8.44 (bt, 1H), 7.82 (d, 2H), 7.32 ((d,2H), 7.04 (broad, 1H), 4.92 (dd, 1H), 4.49 (AB part of an ABX spectrum),4.12 (m, 2H), 4.10 (t, 2H), 3.63 (s, 3H), 3.24 (s, 2H), 2.87 (d, 1H),2.65 (m, 1H), 2.52 (m, 1H), 2.01 (broad, 1H), 1.96 (bd, 2H), 1.75 (q,4H), 1.63 (bdd, 1H), 1.53 (m, 1H), 1.3-1.1 (m, 5H), 0.99 (t, 3H).

[0277]¹³C-NMR (100 MHz, CDCl₃) carbonyl and aridine signals: δ 175.3,172.5, 170.7, 167.7, 165.0.

Example 7 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH₂OMe

[0278] (i) Boc-(R)Cgl-Aze-Pab-COOCH₂CH₂OMe

[0279] The sub-title compound was prepared according to the proceduredescribed in Example 1(i) above using Boc-(R)Cgl-Aze-Pab-H (6.0 g; 13mmol) and 2-methoxyethyl chIoroformate (1.94 g; 14 mmol). Yield 3.9 g(52%).

[0280]¹H-NMR (400 MHz, CDCl₃): δ 8.24 (bt, 1H), 7.83 (d, 2H), 7.31 (d,2H), 5.08 (bd, 1H), 4.87 (dd, 1H), 4.58 (dd, 1H), 4.39 (dd, 2H), 4.30(t, 2H), 4.15 (m, 1H), 3.79 (bt, 1H), 3.68 (t, 2H), 3.40 (s, 3H),2.65-2.45 (m, 2H), 2.20 (broad, 1H), 1.9-1.55 (m, 6H), 1.34 (s, 9H),1.34-0.95 (m, 6H).

[0281]¹³C-NMR (100 MHz, CDCl₃) carbonyl and amidine signals: δ 172.7,170.7, 167.8, 164.6, 155.9.

[0282] (ii) H—(R)Cgl-Aze-Pab-COOCH₂CH₂OMe×2TFA

[0283] The sub-title compound was prepared according to the proceduredescribed in Example 1(ii) above using 1.71 g ofBoc-(R)Cgl-Aze-Pab-COOCH₂CH₂OMe (from step (i) above). Yield 1.89 g(88%).

[0284]¹H-NMR (400 MHz, MeOH-d4): δ 7.77 (d, 2H), 7.59 (d, 2H), 4.85 (dd,1H), 4.56 (d, 2H), 4.49 (m, 2H), 4.37 (m, 1H), 4.28 (m, 1H), 3.70 (m,3H), 3.37 (s, 3H), 2.68 (m, 1H), 2.28 (m, 1H), 1.9-1.7 (m, 7H), 1.4-1.1(m, 6H).

[0285]¹³C-NMR (100 MHz, MeOH-d4) carbonyl and amidine signals: δ 172.7,169.3, 168.0, 154.6.

[0286] (iii) EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH₂OMe

[0287] The title compound was prepared according to the proceduredescribed in Example 1(iii) above fromH—(R)Cgl-Aze-Pab-COOCH₂CH₂OMe×2TFA (487 mg; 0.69 mmol; from step (ii)above) and ethyl bromoacetate (138 mg; 0.83 mmol) to give a crudeproduct which was purified by flash chromatography using THF:methylenechloride (3:1) as eluent. The yield was 0.13 mg (34%) as a white solid.

[0288]¹H-NMR (400 MHz, CDCl₃): δ 8.46 (bt, 1H), 7.83 (d, 2H), 7.32 (d,2H), 7.21 (broad, 1H), 4.92 (dd, 1H), 4.49 (AB part of an ABX spectrum,2H), 4.30 (t, 2H), 4.12 (q, 2H), 4.07 (q, 2H), 3.68 (t, 1H), 3.40 (s,3H), 3.24 (s, 2H), 2.62 (m, 1H), 2.52 (m, 1H), 2.07 (broad, 1H), 1.97(bd, 1H), 1.8-1.5 (m, 5H), 1.3-1.1 (m, 6H), 1.05-0.95 (m, 2H).

[0289]¹³C-NMR (100 MHz, CDCl₃) carbonyl and amidine signals: δ 175.3,172.2, 170.7, 167.8, 164.6.

Example 8 MeOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH₂OMe

[0290] The title compound was prepared according to the method describedin Example 1(iii) above from H—(R)Cgl-Aze-Pab-COOCH₂CH₂OMe×2TFA (490 mg;0.7 mmol; see Example 7(ii) above) and methyl bromoacetate (128 mg; 0.84mmol) to give a crude product which was purified by flash chromatographyusing THF:methylene chloride (3:1) as eluent. The yield was 155 mg (41%)as a white solid.

[0291]¹H-NMR (400 MHz, CDCl₃): δ 8.44 (t, 1H), 7.83 (d, 2H), 7.31 (d,2H), 4.92 (dd, 1H), 4.49 (AB part of an ABX spectrum, 2H), 4.30 (t, 2H),4.13 (m, 2H), 3.68 (t, 2H), 3.63 (s, 3H), 3.39 (s, 3H), 3.25 (s, 2H),2.87 (d, 1H), 2.62 (m, 1H), 2.52 (m, 1H), 1.96 (bd, 1H), 1.8-1.5 (m,6H), 1.3-1.1 (m, 5H), 1.00 (q, 2H).

[0292]¹³C-NMR (100 MHz, CDCl₃) carbonyl and amidine signals: δ 175.2,172.6, 170.7, 167.8, 164.5.

Example 9 EtOOCCH₂—(R)Cgl-Aze-Pab-COO-nBu

[0293] (i) Boc-(R)Cgl-Aze-Pab-COO-nBu

[0294] The sub-title compound was prepared according to the proceduredescribed in Example 1(i) from Boc-(R)Cgl-Aze-Pab-H (1.01 g; 2.1 mmol)and n-butyl chloroformate (0.32 g; 2.4 mmol). After stirng at ambienttemperature for 1.5 h the reaction mixture was concentrated andextracted with three portions of methylene chloride. The combinedorganic phase was then washed with water, dried over Na₂SO₄, andconcentrated to give 1.0 g (83%) of the sub-title compound as a whitesolid.

[0295]¹H-NMR (300 MHz, CDCl₃): δ 9.81-9.31 (bs, 1H), 8.36-8.20 (m, 1H),7.35 (d, 2H), 7.84 (d, 2H), 6.78-6.43 (bs, 1H), 5.05-4.82 (m, 2H),4.69-4.15 (m, 3H), 4.15-4.08 (m, 3H), 3.86-3.70 (m, 1H), 2.68-2.42 (m,2H), 1.92-0.88 (m, 25H).

[0296]¹³C-NMR (125 MHz, CDCl₃) amidine and carbonyl signals: δ 172.5,170.7, 167.9, 164.9, 156.0.

[0297] FAB-MS: (m+1)=572 (m/z)

[0298] (ii) H—(R)Cgl-Aze-Pab-COO-nBu×2HCl

[0299] The sub-title compound was prepared according to the proceduredescribed in Example 4(ii) from Boc-(R)Cgl-Aze-Pab-COO-nBu (2.5 g; 4.4mmol; from step (i) above) to give 2.4 g (100%) as a white solid.

[0300]¹H-NMR (300 MHz, MeOH-d4): δ 7.78-7.60 (m, 2H), 4.66-4.49 (m, 2H),0.98 (t, 2H), 4.49-4.35 (m, 3H), 4.35-4.22 (m, 1H), 3.75 (d, 1H),1.92-1.67 (m, 8H), 1.56-1.07 (m, 8H). The signal of one of the protonsis partially obscured by the CD₃OH-signal

[0301]¹³C-NMR (100 MHz, MeOH-d4) amidine and carbonyl signals: δ 172.7,169.3, 167.9, 154.7

[0302] MS (m+1)=472 (m/z)

[0303] (iii) EtOOCCH₂—(R)Cgl-Aze-Pab-COO-nBu

[0304] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-nBu×2HCl (400 mg;0.74 mmol) and ethyl bromoacetate (147 mg; 0.88 mmol). The product waspurified by flash chromatography using methylene chloride and EtOHgradient 0.1%=>12.8% as eluent to give 290 mg (70%) as a white solid.

[0305]¹H-NMR (300MHz, CDCl₃): δ 9.70-9.36 (bs, 1H), 8.47 (t, 1H), 7.81(d, 2H), 7.32 (d, 2H), 7.07-6.73 (bs, 1H), 4.97-4.87 (dd, 1H), 4.62-4.35(m, 2H), 4.20-3.98 (m, 6H), 3.27-3.12 (m, 2H), 2.84 (s, 1H), 2.70-2.40(m, 2H), 2.03-0.85 (m, 22H)

[0306]¹³C-NMR (75MHz, CDCl₃) amidine and carbonyl signals: δ 175.3,172.3, 170.8, 167.9, 165.0

[0307] FAB-MS: (m+1)=558 (m/z)

Example 10 PrlC(O)CH₂CH₂CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0308] (i) PrlC(O)CH₂CH₂CH₂OH

[0309] A mixture of γ-butyrolactone (4.0 g; 46.5 mmol) and pyrrolidine(6.6 g; 92.8 mmol) was stirred at room temperature for 2.5 h. Theproduct was concentrated in vacuum to give 14.5 g (100%) of the productas a yellow oil.

[0310]¹H-NMR (300 MHz, MeOH-d4): δ 3.58 (t, 2H), 3.50 (t, 2H), 3.40 (t,2H), 2.42 (t, 2H), 2.06-1.75 (m, 6H)

[0311] (ii) PrlC(O)CH₂CH₂OOCCH₂Br

[0312] To a mixture of PrlC(O)CH₂CH₂CH₂OH (7.2 g; 45.8 mmol; from step(i) above) and DMAP (5.6 g; 45.8 mmol) in methylene chloride at 0° C.was added dropwise bromoacetyl bromide (4.0 mL; 45.8 mmol). Afterstirring at room temperature for 1.5 h another portion of bromoacetylbromide (1.0 mL, 11.4 mmol) and DMAP (1.4 g, 11.4 mmol) was added andreaction was refluxed for 1.5 h. Water was added and the methylenechloride was extracted 3 times. The organic phase was dried with Na₂SO₄and concentrated to give 10.3 g (81%) of the product as a yellow oil.

[0313]¹H-NMR (400 MHz, CDCl₃): δ 4.15 (t, 2H), 3.75 (s, 2H), 3.40-3.31(m, 4H), 2.30 (t, 2H), 1.98-1.83 (m, 4H), 1.81-1.73 (m, 2H)

[0314] (iii) PrlC(O)CH₂CH₂CH₂OOCCH₂—(R)Cgl-Aze-Pab(Z)

[0315] The title compound was prepared according to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z (6 g; 10.4 mmol) andPrlC(O)CH₂CH₂CH₂OOCCH₂Br (3.5 g; 12.4 mmol; from step (ii) above). Thecrude product was purified by flash chromatography usingheptane:EtOAc:isopropanol (1:2:2) as eluent to give 4.2 g which was thenpurified by using preparative RPLC using 44% acetonitrile in 0.1M NH₄OAcas eluent to give 2.64 g (36%) of the product as a white solid.

[0316]¹H-NMR (500 MHz, CDCl₃): δ 9.80-9.22 (b s, 1H), 8.36 (t, 1H),7.96-7.58 (m, 3H), 7.45 (d, 2H), 7.37-7.22 (m, 5H), 5.20 (s, 2H),4.95-4.88 (dd, 1H), 4.72-4.29 (m, 2H), 4.15-4.04 (m, 2H), 4.04 -3.88 (m,2H), 3.40 (t, 2H), 3.34 (t, 2H), 3.28 -3.17 (m, 2H), 2.85 (d, 1H),2.67-2.48 (m, 1H), 2.23 (t, 2H), 2.14-0.93 (m, 18H).

[0317]¹³C-NMR (125 MHz, CDCl₃) amidine and carbonyl signals: δ 175.3,172.4, 170.9, 170.4, 168.2, 164.6

[0318] FAB-MS: (m+1)=703 (m/z)

Example 11 ChNHC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0319] (i) ChNHC(O)CH₂OH

[0320] A mixture of cyclohexylamine (9.9 g; 99.8 mmol) and2,5-dioxo-1,4-dioxane (3.0 g, 25.9 mmol) was stirred at 100° C. for 2.5h. The product was concentrated to give 8.1 g (100%) of the product as abrown solid.

[0321]¹H-NMR (500 MHz, MeOH-d4): δ 3.92 (s, 2H), 3.75-3.65 (m, 1H),1.90-1.58 (m, 5H), 1.43-1.07 (m, 5H). The signal of two of the protonsare obscured by the CD₃OH-signal.

[0322]¹³C-NMR (125 MHz, MeOH-d4) amidine and carbonyl signals: δ 174.0,62.5, 33.7, 26.5, 26.1, 26.0 The signal of one of the carbons isobscured by the CD₃OD-signal.

[0323] (ii) ChNHC(O)CH₂OOCCH₂Br

[0324] To a mixture of ChNHC(O)CH₂OH (8.0 g; 50.9 mmol; from step (i)above) and DMAP (6.2 g; 50.9 mmol) in methylene chloride (80 mL) at 0°C. was added dropwise bromoacetyl bromide (4.0 mL; 45.8 mmol). Afterstirring at room temperature for 1.5 h further portions of bromoacetylbromide (1.0 mL, 11.4 mmol) and DMAP (1.4 g, 11.4 mmol) were added andthe reaction mixture was refluxed for 1.5 h. Water was added and theaqueous phase was extracted with three portions of methylene chloride.The organic phase was washed with water, dried with Na₂SO₄, andconcentrated to give 10.3 g (73%) of the product as a brown solid.

[0325]¹H NMR (400 MHz, CDCl₃): δ 6.12-6.00 (bs, 1H), 4.62 (s, 2H), 3.90(s, 2H), 3.84-3.76 (m, 1H), 1.95-1.86 (m, 2H), 1.75-1.65 (m, 2H),1.65-1.56 (m, 1H), 1.43-1.29 (m, 2H), 1.24-1.10 (m, 3H).

[0326] (iii) ChNHC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0327] The title compound was prepared analogously to the proceuredescribed in Example 1(iii) with starting from H—(R)Cgl-Aze-Pab-Z (6 g;10.4 mmol) and ChNHC(O)CH₂OOCCH₂Br (3.5 g; 12.4 mmol; from step (ii)above). The crude product was purified by flash chromatography usingheptane:EtOAc:isopropanol (5:2:2) as eluent followed by concentrationand then by preparative RPLC using 50% acetonitrile in 0.1M NH₄OAc aseluent. Concentration and freeze drying gave 2.6 g (36%) of the productas a white solid.

[0328]¹H-NMR (500 MHz, CDCl₃): δ 9.78-9.25 (bs, 1H), 7.90 (t, 1H), 7.78(d, 2H), 7.44 (d, 2H), 7.38-7.24 (m, 5H), 6.66 (t, 1H), 5.20 (s, 2H),4.90-4.83 (dd, 1H), 4.60-4.45 (m, 2H), 4.18-3.93 (m, 4H), 3.73-3.62 (m,1H), (d, 1H), 3.23, 3.44 (AB, 2H), 2.87, 2.65-2.08 (m, 3H), 1.98-0.93(m, 22H)

[0329]¹³C-NMR (125 MHz, CDCl₃) amidine and carbonyl signals: δ 175.1,171.7, 170.7, 168.8, 166.1, 164.4

[0330] FAB-MS: (m+1)=703 (m/z)

Example 12 (nPr)₂NC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃

[0331] (i) (nPr)₂NC(O)CH₂OH

[0332] A mixture of 2,5-dioxo-1,4-dioxane (2.02 g; 17.4 mmol) anddi-n-propylamine (5 ml; 36.5 mmol) was heated at 50° C. for 1 h and at90° C. for 66 h. Toluene was added and subsequently removed in vacuowith excess di-n-propylamine. The residue was purified by flashchromatography using 10% methanol in methylene chloride as eluent togive 4.18 g (66%) of the desired compound.

[0333]¹H NMR (300 MHz, CDCl3): δ 4.1 (d, 2 H), 3.65 (t, 1 H), 3.25-3.35(m, 2 H), 2.9-3.0 (m, 2 H), 1.45-1.6 (m, 4 H), 0.8-0.95 (m, 6 H)

[0334] (ii) (nPr)₂NC(O)CH₂OOCCH₂Br

[0335] A mixture of (nPr)₂NC(O)CH₂OH (0.743 g; 4.7 mmol; from step (i)above), DCC (0.951 g, 4.6 mmol), and bromoacetic acid (0.704 g; 5.1mmol) in methylene chloride (15 ml) was stirred at room temperature for1.5 h. The precipitate was removed by filtration and the solvent wasremoved from the filtrate in vacuo. Kugelrohr distillation of theresidue gave 0.66 g (50%) of the desired compound.

[0336]¹H NMR (300 MHz, CDCl3): δ 4.8 (s, 2 H), 4.0 (s, 2 H), 3.2-3.3 (m,2 H), 3.05-3.15 (m, 2 H), 1.5-1.7 (m, 4 H), 0.8-1.0 (dt, 6 H)

[0337] (iii) Pivaloyloxymethyl 4-nitrophenyl carbonate

[0338] A mixture of silver pivalate (7.5 g; 25 mmol) and iodomethyl4-nitrophenyl carbonate (Alexander et al, J. Med. Chem. (1988) 31, 318;7.99 g; 25 mmol) was refluxed in benzene (50 ml) for 2 h. The benzenewas removed in vacuo and the residue was dissolved in toluene.Filtration through hyflo and purification by flash chromatography usingtoluene as eluent afforded 4.00 g (54%) of the sub-title compound.

[0339]¹H NMR (300 MHz; CDCl₃): δ 8.25 (d, 2 H), 7.40 (d, 2 H), 5.85 (s,2 H), 1.2 (s, 2 H)

[0340]¹³C NMR (75 MHz, CDCl₃) amidine and carbonyl signals: δ 176.77,155.06

[0341] (iv) Boc-(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃

[0342] A solution of pivalyloxymethyl 4-nitrophenyl carbonate (1.18 g; 4mmol; from step (iii) above) in methylene chloride (20 ml) was added atroom temperature to a solution of Boc-(R)Cgl-Aze-Pab-H (1.88 g; 4 mmol)and triethylamine (0.66 ml; 4.75 mmol) in methylene chloride (20 ml).After 1 h the methylene chloride was replaced by EtOAc and the mixturewas purified by flash chromatography using EtOAc as eluent to give 1.27g (50%) of sub-title compound.

[0343]¹H NMR (300 MHz, CDCl₃): δ 9.5 (bs, 1 H), 8.25 (t, 1 H), 7.8 (d, 2H), 7.3 (d, 2 H), 7.0 (bs, 1 H), 5.0-4.8 (m, 2 H), 4.65-4.5 (m, 1 H),4.5-4.3 (m, 2 H), 4.2-4.05 (m, 1 H), 3.75 (t, 1 H), 2.7-2.4 (m, 2 H),1.9-1.45 (m, 5 H), 1.45-0.8 (m, 24 H)

[0344] (v) H—(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃

[0345] Boc-(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃ (327 mg; 0.52 mmol; from step(iv) above) was dissolved in a mixture of methylene chloride (5 ml) andTFA (1.2 ml). After 2 h the reaction mixture was concentrated in vacuo,acetonitrile was added, and the solvent was again removed in vacuo togive crude sub-title product which was used without further purificationin the next step.

[0346] (vi) (nPr)₂NC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃

[0347] The residue from step (v) above was mixed with(nPr)₂NC(O)CH₂OOCCH₂Br (150 mg; 0.53 mmol; from step (ii) above) andK₂CO₃ (480 mg; 3.5 mmol) in THF (5 ml) and heated for 3 h at 40° C. Thereaction mixture was filtered and concentrated to a crude product whichwas purified by preparative RPLC to give 78 mg (21%) of the titlecompound.

[0348]¹H NMR (300 MHz, CDCl₃): δ 9.3-9.6 (bs, 1 H), 8.5 (m, 1 H),7.95-8.15 (bs, 1 H), 7.85-7.95 (d, 2 H), 7.2-7.3 (d, 2 H), 5.8 (s, 2 H),4.8-4.9 (dd, 1 H), 4.5-4.7 (m, 3 H), 4.0-4.4 (m, 3 H), 2.8-3.4 (m, 5 H),2.2-2.7 (m, 3 H), 1.75-1.3 (m, 9 H), 1.3-1.0 (m, 14 H), 1.0-0.7 (m, 7H).

[0349]¹³C NMR (75 MHz, CDCl3) amidine and carbonyl signals: δ 177.24,175.30, 171.85, 170.79, 168.78, 165.82, 163.14.

Example 13 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃

[0350] The title compound was prepared analogously to to the proceduredescribed in Example 12(vi) above from crude Boc-(R)Cgl-Aze-PabCOOCH₂OOCC(CH₃)₃ (0.41 g; 0.65 mmol; see Example 12(iv) above) usingacetonitrile (10 ml) as solvent. After stirring over night at roomtemperature, the solvent was removed in vacuao and the residue waspartitioned between EtOAc and water. The aqueous phase was extractedthree times with EtOAc and the combined organic phases were dried(Na₂SO₄) and the solvent was removed in vacua. The residue was subjectedto flash chromatography using methylene chloride/methanol as eluent.Freeze drying from glacial acetic acid gave 84 mg (21%) of the titlecompound.

[0351]¹H NMR (300 MHz, CDCl3): δ 9.9 (bs, 1 H), 8.5 (t, 1 H), 7.35 (d, 2H), 5.85 (s, 2 H), 5.90 (dd, 2 H), 4.6-4.35 (m, 2 H), 4.15-4.0 (m, 4),3.2 (s, 2 H), 2.85 (d, 1 H), 2.7-2.45 (m, 2), 2.0-1.9 (m, 2 H), 1.8-1.45(m, 5 H), 1.3-0.9 (m, 18 H).

[0352]¹³C NMR (75 MHz, CDCl3) amidine and carbonyl signals: Δ 177.23,175.48, 172.29, 170.80, 168.85, 163.14.

Example 14 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH(CH₃)OOCCH₃

[0353] (i) Boc-(R)Cgl-Aze-Pab-COOCH(CH₃)OOCCH₃

[0354] A solution of Boc-(R)Cgl-Aze-Pab-H (6.38 g; 13.5 mmol),1-acetoxyethyl 4-nitrophenyl carbonate (Alexander et al, J. Med. Chem.(1988) 31, 318) (3.05 g; 12 mmol), and triethylamine (1.95 ml; 14 mmol)in methylene chloride (40 ml) was stirred at room temperature for 16 hfollowed by addition of EtOAc. The resulting solution was slightlyconcentrated and washed with aqueous Na₂CO₃ (10%), concentrated to acrude product, which was purified by flash chromatography using EtOAc aseluent, to give 5.59 g (77%) of the sub-title compound.

[0355]¹H NMR (300 MHz, CDCl3): δ 9.5 (bs, 1 H), 8.25 (t, 1 H), 7.85 (d,2 H), 7.35 (d, 2 H), 6.95 (q, 1 H), 6.7 (bs, 1 H), 5.0-4.85 (m, 2 H),4.65-4.5 (m, 1 H), 4.5-4.25 (m, 2 H), 4.2-4.05 (m, 1 H) 3.75 (t, 1 H),2.65-2.45 (m, 2 H) 2.05 (s, 3 H), 1.9-1.45 (m, 11 H), 1.45-0.8 (m, 12H).

[0356]¹³C NMR (75 MHz, CDCl3) amidine and carbonyl signals: δ 172.61,170.80, 169.54, 168.91, 162.50, 156.02.

[0357] (ii) H—(R)Cgl-Aze-Pab-COOCH(CH₃)OOCCH₃

[0358] The crude sub-title compound was prepared according to theprocedure described in Example 12(v) above fromBoc-(R)Cgl-Aze-Pab-COOCH(CH₃)OOCCH₃ (2.21 g; 3.68 mmol; from step (i)above).

[0359] (iii) EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH(CH₃)OOCCH₃

[0360] The crude H—(R)Cgl-Aze-Pab-COOCH(CH₃)OOCCH₃ from step (ii) abovewas dissolved in methylene chloride (150 mL). The mixture was washedwith a 10% Na₂CO₃ solution and the organic phase was dried with K₂CO₃and filtered. To the resulting solution as added K₂CO₃ (756 mg, 5.5mmol) and ethyl (O-trifluoromethanesulphonyl)-glycolate (790 mg; 3.3mmol) in methylene chloride (5 ml). The reaction mixture was stirred for5-10 minutes at room temperature and then concentrated in vacuo. Theresidue was dissolved in EtOAc and the resulting mixture was filteredthrough celite. The filtrate was subjected to flash chromatography usingEtOAc as eluent followed by HPLC to give 475 mg (22%) of the titlecompound.

[0361]¹H NMR (300 MHz, CDCl3): δ 9.5 (bs, 1 H), 8.3 (t, 1 H), 7.7 (d, 2H), 7.2 (d, 2 H), 6.85 (q, 1 H), 4.8 (t, 1 H), 4.45-4.25 (m, 2 H),4.1-3.85 (m, 4 H), 3.1 (s, 2 H), 2.75 (s, 1 H), 2.5-2.3 (m, 2 H),1.95(s, 3 H), 1.9-1.8 (m, 1 H), 1.7-1.25 (m, 8 H), 1.25-1.75 (m, 8 H).

[0362]¹³C NMR (75.5 MHz, CDCl3) amidine and carbonyl signals: δ 175.26,172.34, 170.81, 169.49, 168.80, 162.43.

Example 15 MeOOCCH₂—(R)Cgl-Aze-Pab-OOCPh

[0363] (i) Boc-(R)Cgl-Aze-Pab-OOCPh

[0364] To a solution of Boc-(R)Cgl-Aze-Pab-H (1.0 g; 2.1 mmol) andNa₂HPO₄ (18.7 g; 105 mmol) in THF (45 mL) at 20° C. was added dropwisedibenzoyl peroxide (556 mg; 2.3 mmol) dissolved in THF (10 mL) over 45minutes. After stirring at 20° C. for 24 h, the reaction mixture wasconcentrated and the resulting crude product was subjected topreparative RPLC. This gave 124 mg (10%) of the sub-title compound as awhite solid.

[0365]¹H-NMR (500 MHz, CDCl₃): δ 8.26 (m, 1H), 8.09 (m, 2H), 7.72 (m,2H), 7.59 (m, 1H), 7.48 (m, 2H), 7.36 (d, 2H), 5.13 (s, 2H), 4.87-4.98(m, 2H), 4.54-4.61 (m, 1H), 4.33-4.47 (m, 2H), 4.13-4.19 (m, 1H), 3.81(t, 1H), 2.53-2.63 (m, 2H), 1.73-1.86 (m, 3H), 1.661.72 (m, 2H), 1.36(s, 9H), 0.968-1.28 (m, 6H).

[0366]³C-NMR (100 MHz, CDCl3) amidine and carbonyl signals: δ 172.7,170.6, 163.9, 157.0, 155.9.

[0367] LC-MS: m/z 592 (M+H⁺); m/z 614 (M+Na⁺).

[0368] (ii) H—(R)Cgl-Aze-Pab-OOCPh

[0369] To a solution of Boc-(R)Cgl-Aze-Pab-OOCPh (600 mg; 1.01 mmol;from step (i) above) in methylene chloride (18 mL) was added TFA (6 mL)at 20° C. After stirring for 14 h, the reaction mixture was concentratedand s the resulting crude product was partitioned between EtOAc:0.1 MNaOH. The phases were separated and the organic layer was dried (Na₂SO₄)and evaporated. Yield: 480 mg (96%) as a white solid.

[0370]¹H-NMR (400 MHz, MeOH-d4): δ 8.18 (m, 2H), 7.77 (m, 2H), 7.64 (m,1H), 7.52 (m, 2H), 7.43 (d, 2H), 4.75-4.81 (m, 1H), 4.50 (s, 2H),4.18-4.34 (m, 2H), 3.12 (d, 1H), 2.57-2.68 (m, 1H), 2.23-2.33 (m, 1H),1.88-1.96 (m, 1H), 1.73-1.84 (m, 2H), 1.59-1.71 (m, 2H), 1.45-1.57 (m,1H), 0.80-1.34 (m, 5H)

[0371] LC-MS: m/z 492 (M+H⁺); m/z 514 (M+Na⁺)

[0372] (iii) MeOOCCH₂—(R)Cgl-Aze-Pab-OOCPh

[0373] To a solution of H—(R)Cgl-Aze-Pab-OOCPh (480 mg; 0.97 mmol; fromstep (ii) above), K₂CO₃ (270 mg; 2 mmol) in acetonitrile (5 mL) at 20°C. was added methyl bromoacetate (177 mg; 1.16 mmol). The reaction wasstirred at 20° C. for 14 h. The reaction mixtture was filtered andconcentrated to give a crude product which was purified by preparativeRPLC to give gave 269 mg (49%) of the title compound as a white solid.

[0374]¹H-NMR (500 MHz, CDCl₃): δ 8.43 (m, 1H, NH), 8.09 (m, 2H), 7.69(m, 2H), 7.59 (m, 1H), 7.47 (m, 2H), 7.34 (m, 2H), 5.27 (s, 2H), 4.93(dd, 1H), 4.59 (dd, 1H), 4.40 (dd, 1H), 4.12 (m, 2H), 3.65 (s, 3H), 2.87(d, 1H), 2.72-2.63 (m, 1H), 2.55-2.48 (m, 1H), 1.96 (m, 1H), 1.74 (m,2H), 1.67 (d, 1H), 1.59 (d, 1H), 1.56-1.50 (m, 1H), 1.29-1.08 (m, 4H),1.04-0.94 (m, 1H)

[0375]¹³C-NMR (100 MHz, CDCl₃) amidine and carbonyl signals: δ 175.1,172.5, 170.6, 164.0, 157.1

[0376] LC-MS: m/z 564 M+H⁺)

Example 16 MeOOCCH₂—(R)Cgl-Aze-Pab-OH

[0377] To a solution of MeOOCCH₂—(R)Cgl-Aze-PabOC(O)Ph (260 mg; 0.46mmol; see Example 15(iii) above) in THF (4.6 mL) was added KOMe (1.6 mL;0.29 M; 0.46 mmol) at 20° C. After 15 minutes of stirring the mixturewas concentrated and subjected to preparative RPLC. This gave 109 mg(52%) of the title compound as a white solid.

[0378]¹H-NMR (500 MHz, MeOH-d4): δ 7.59 (d, 2H), 7.34 (d, 2H), 4.83 (s,2H), 4.82-4.76 (m, 1H), 4.48 (d, 1H), 4.33 (d, 1H), 4.15-4.30 (m,2H),3.64 (s, 3H), 3.04 (d, 1H), 2.57 (m, 1H), 2.26 (m, 1H), 1.95 (m, 1H),1.75 (m, 2H), 1.58-1.70 (m, 2H), 1.53 (m, 1H), 1.31-1.10 (m, 4H), 1.04(m,1H)

[0379]¹³C-NMR (100 MHz, MeOH-d4): amidine and carbonyl signals: δ 175.9,174.3, 172.7, 155.2

[0380] LC-MS: m/z 460 (M+H⁺), m/z 482 (M+Na⁺)

Example 17 EtOOCCH₂—(R)Cgl-Aze-Pab-OH

[0381] To a solution of EtOOCCH₂—(R)Cgl-Aze-PabC(O)OCH(CH₃)OOCCH₃ (184mg; 0.31 mmol; see Example 14(iia) above), hydroxylamine hydrochloride(120 mg; 1.72 mmol) and triethylamine (0.8 ml; 5.7 mmol) in EtOH (95%;4.0 mL) was added, and the mixture stirred at room temperature for 4days. The reaction mixture was concentrated and the crude productsubjected to preparative RPLC. This gave 85 mg (58%) of the titlecompound.

[0382]¹H-NMR (300 MHz, CD₃OD): δ 7.6 (d, 2H), 7.35 (d, 2H), 4.75-4.85(m, 1H), 4.4-4.55 (m, 2H), 4.0-4.35 (m, 4H), 3.35 (d, 2H), 3.05 (d, 1H),2.5-2.65 (m, 1H), 2.2-2.35 (m, 1H), 1.9-2.05 (m, 1H), 1.4-1.85 (m, 5H),0.85-1.35 (m, 8H)

[0383]¹³C-NMR (75.5 MHz, CD₃OD): amidine and carbonyl signals: δ 175.97,173.91, 172.72, 155.23

[0384] LC-MS: (m+1)=474 (m/z)

Example 18 BnOOCCH₂—(R)Cgl-Aze-Pab-OH

[0385] To a solution of hydroxylamine hydrochloride (320 mg; 4.59 mmol)and triethylamine (1.7 ml; 12.24 mmol) in EtOH,BnOOCCH₂—(R)Cgl-Aze-Pab-Z (1.0 g; 1.52 mmol) was added. The reactionmixture was stirred at room temperature for 40 hours and thenconcentrated. The crude product was purified by preparative RPLC using50% acetonitrile in 0.1 M NH₄OAc as eluent to give 0.34 g (42%) of thetitle compound.

[0386] LC-MS:(m+1)=536 (m/z)

Example 19 nPrOOCCH₂—(R)Cgl-Aze-Pab-Z

[0387] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z×2HCl (700 mg; 1.2mmol) and n-propyl bromoacetate (268 mg; 1.45 mmol). Yield 259 mg (35%).

[0388] FAB-MS:(m+1)=606 (m/z)

Example 20 nPrOOCCH₂—(R)Cgl-Aze-Pab-OH

[0389] The title compound was prepared analogously to the proceduredescribed in Example 18 from nPrOOCCH₂—(R)Cgl-Aze-Pab-Z (182 mg; 0.3mmol; see Example 19 above). The crude product was purified bypreparative RPLC using 40% acetonitrile in 0.1M NH₄OAc as eluent to give74 mg (51%) of the desired compound.

[0390] LC-MS:(m+1)=488 (m/z)

Example 21 iPrOOCCH₂—(R)Cgl-Aze-Pab-OH

[0391] The title compound was prepared analogously to the proceduredescribed in Example 18 from iPrOOCCH₂—(R)Cgl-Aze-Pab-Z (590 mg; 0.7mmol; see Example 39 below). Yield 110 mg (32%)

[0392] LC-MS:(m+1)=488 (m/z)

Example 22 tBuOOCCH₂—(R)Cgl-Aze-Pab-OH

[0393] The title compound was prepared analogously to the proceduredescribed in Example 18 from tBuOOCCH₂—(R)Cgl-Aze-Pab-Z (738 mg; 1.2mmol; see Example 37 below). Yield 290 mg (48%).

[0394] LC-MS:(m+1)=502 (m/z)

Example 23

[0395] (nPr)₂NCOCH₂OOCCH₂—(R)Cgl-Aze-Pab(OH)

[0396] (i) HOOCCH₂—(R)Cgl(Boc)-Aze-Pab-O-Boc

[0397] A solution of HOOCCH₂—(R)Cgl-Aze-Pab-OH (670 mg; 1.5 mmol; seeExample 28 below), (Boc)₂O (654 mg; 3 mmol), and DMAP (92 mg; 0.75 mmol)in THF:water (10:1) was stirred at room temperature for 2 h.

[0398] The reaction mixture was concentrated and purified by preparativeRPLC. Freeze drying yielded 112 mg (12%) of the sub-title compound as awhite solid.

[0399] LC-MS:(m−1)=643 (m/z)

[0400] (ii) (nPr)₂NCOCH₂OOCCH₂—(R)Cgl(Boc)-Aze-Pab-O-Boc

[0401] A solution of HOOCCH₂—(R)Cgl(Boc)-Aze-Pab-O-Boc (100 mg; 0.15mmol; from step (i) above), (nPr)₂NCOCH₂OH (27 mg; 0.17 mmol; seeExample 12(i) above), EDC (40 mg; 0.21 mmol) and DMAP (10 mg; 0.075mmol) in acetonitrile (5 mL) was stirred at room temperature for 4 days.The reaction mixture was concentrated, purified by preparative RPLC andfreeze dried to give 21 mg (18%) of the sub-title compound.

[0402] LC-MS: (m−1)=787 (m/z)

[0403] (iii) (nPr)₂NCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-OH

[0404] A solution of (nPr)₂NCOCH₂—(R)Cgl(Boc)-Aze-Pab-O-Boc (20 mg;0.025 mmol) in TFA:methylene chloride (1:1) was stirred at roomtemperature for 5 minutes. The reaction mixture was concentrated andfreeze dried from acetonitrile and water to give 5 mg (34%) of the titlecompound.

[0405] LC-MS: (m+1)=587 (m/z)

Example 24 ChNHCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-OH

[0406] The title compound was prepared analogously to the proceduredescribed in Example 18 from ChNHCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-Z (118 mg;0.17 mmol; see Example 11(iii) above). Yield 1.8 mg.

[0407] LC-MS:(m+1)=585 (m/z)

Example 25 MeNHCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-OH

[0408] The title compound was prepared analogously to the proceduredescribed in Example 18 from MeNHCOCH₂—(R)Cgl-Aze-Pab-Z (81 mg; 0.12mmol, see Example 36 below). Yield 10 mg (16%).

[0409] LC-MS:(m+1)=517 (m/z)

Example 26 EtOOCCH₂—(R)Cgl-Aze-Pab-OAc

[0410] (i) H—(R)Cgl-Aze-Pab-OAc

[0411] The sub-title compound was prepared analogously to the methoddescribed in Example 27 below (steps (i), (ii) and (iii)) using aceticacid anhydride instead of propanoic acid anhydride.

[0412] LC-MS:(m+1)=430 (m/z)

[0413] (ii) EtOOCCH₂—(R)Cgl-Aze-Pab-OAc

[0414] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) above from H—(R)Cgl-Aze-Pab-OAc (370 mg; 0.6mmol) and ethyl bromoacetate (105 mg; 0.63 mmol). Yield 67 mg (22%).

[0415] LC-MS:(m+1)=516 (m/z)

Example 27 EtOOCCH₂—(R)Cgl-Aze-Pab-O)C(O)Et

[0416] (i) Boc-(R)Cgl-Aze-Pab-OH

[0417] To a solution of hydroxylamine hydrochloride and triethylamine inEtOH was added Boc-(R)Cgl-Aze-Pab-Z (1.0 g; 1.52 mmol). The reactionmixture was stirred at room temperature for 40 hours and thenconcentrated. The crude product was purified by preparative RPLC.

[0418] LC-MS: (m+1)=488 m/z

[0419] (ii) Boc-(R)Cgl-Aze-Pab-OC(O)Et

[0420] A solution of Boc-(R)Cgl-Aze-Pab-OH (500 mg; 0.91 mmol; from step(i) above) and propanoic acid anhydride (3.5 mL) was stirred at roomtemperature for 45 minutes and then concentrated. The crude product waspurified by preparative RPLC using 50% acetonitrile in 0.1M NH₄OAc aseluent to give 266 mg (54%) of the sub-title compound.

[0421] LC-MS: (m+1)=544 (m/z)

[0422] (iii) H—(R)Cgl-Aze-Pab-OC(O)Et

[0423] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(ii) from Boc-(R)Cgl-Aze-Pab-OC(O)Et (238 mg; 0.44mmol; from step (ii) above). Yield 290 mg (100%).

[0424] LC-MS:(m+1)=444 (m/z)

[0425] (iv) EtOOCCH₂—(R)Cgl-Aze-Pab-OC(O)Et

[0426] To a solution of H—(R)Cgl-Aze-Pab-OOCEt (300 mg; 0.45 mmol; fromstep (iii) above) and K₂CO₃ (308 mg; 2.23 mmol) in methylene chloride (6mL) at 0° C. was added dropwise EtOOCCH₂OSO₂CF₃ (105 mg; 0.45 mmol,prepared from triflic anhydride and ethyl glycolate). After the reactionmixture was stirred at room temperature for 1 h the reaction mixture waswashed with water, citric acid and water, dried (Na₂SO₄) andconcentrated. The crude product was purified by preparative RPLC using45% acetonitrile in 0.1M NH₄OAc as eluent to give 63 mg (27%) of thetitle compound.

[0427] LC-MS: (m+1)=530(m/z)

Example 28 HOOCCH₂—(R)Cgl-Aze-Pab-OH

[0428] (i) tBuOOCCH₂—(R)Cgl-Aze-Pab-OOCPh

[0429] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-OOCPh (250 mg; 0.5mmol; see Example 15(ii) above) and t-butylbromoacetate (119 mg; 0.6mmol). Yield 211 mg (69%).

[0430] LC-MS:(m+1)=606 (m/z)

[0431] (ii) HOOCCH₂—(R)Cgl-Aze-Pab-OOCPh

[0432] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(ii) from tBuOOCCH₂—(R)Cgl-Aze-Pab-OOCPh (233 mg;0.3 mmol; from step (i) above). Yield 65 mg (37%).

[0433] LC-MS:(m+1)=550 (m/z)

[0434] (iii) HOOCCH₂—(R)Cgl-Aze-Pab-OH

[0435] A solution of HOOCCH₂—(R)Cgl-Aze-Pab-OOCPh (60 mg; 0.1 mmol; fromstep (ii) above) and KOMe (0.2M; 0.2 mmol) in THF (10 mL) and methanol(1.5 mL) was stirred at room temperature for 5 minutes. The reactionmixture was concentrated and freeze dried from water and acetonitrile togive 28 mg (63%) of the title compound.

[0436] LC-MS:(m+1)=446(m/z)

Example 29 HOOCCH₂—(R)Cgl-Aze-Pab-O-cis-Oleyl

[0437] (i) tBuOOCCH₂—(R)Cgl(Boc)-Aze-Pab-Z

[0438] A solution of tBuOOCCH₂—(R)Cgl-Aze-Pab-Z (1.7 g, 2.8 mmol; seeExample 37 below), (Boc)₂O (672 mg; 3.08 mmol) and DMAP (68 mg; 0.56mmol) in THF (30 mL) was stirred at room temperature for 24 h.Additional (Boc)₂O (305 mg; 1.4 mmol) was added at 5° C. After another24 h the reaction mixture was concentrated and purified by preparativeRPLC to give 587 mg (30%) of the desired compound.

[0439] EC-MS:(m+1)=720 (m/z)

[0440] (ii) tBuOOCCH₂—(R)Cgl(Boc)-Aze-Pab-OH

[0441] The sub-title compound was prepared analogously to the proceduredescribed in Example 18 from tBuOOCCH₂—(R)Cgl(Boc)-Aze-Pab-Z (580 mg;0.8 mmol; from step (i) above). Yield 341 mg (71%).

[0442] EC-MS:(m+1)=602 (m/z)

[0443] (iii) tBuOOCCH₂—(R)Cgl(Boc)-Aze-Pab-O-cis-Oleyl

[0444] A solution of tBuOOCCH₂—(R)Cgl(Boc)-Aze-Pab-OH (340 mg; 0.56mmol; from step (ii) above), cis-oleylchloride (170 mg; 0.56 mmol) andtriethylamine (62 mg; 0.61 mmol) in methylene chloride was stirred for 5minutes. The reaction mixture was concentrated and purified bypreparative RPLC to give 326 mg (67%) of the sub-itle compound.

[0445] EC-MS:(m+1)=867(m/z)

[0446] (iv) HOOCCH₂—(R)Cgl-Aze-Pab-O-cis-Oleyl

[0447] The title compound was prepared analogously to the proceduredescribed in Example 1(ii) fromtBuOOCCH₂—(R)Cgl(Boc)-Aze-Pab-O-cis-Oleyl (223 mg; 0.25 mmol; from step(iii) above).

[0448] LC-MS: (m+1)=710 (m/z)

Example 30 Cyclooctyl-OOCCH₂-(R)Cgl-Aze-Pab-Z

[0449] (i) Cyclooctyl-bromoacetate

[0450] Cyclooctanol (1.3 g; 10 mmol) and DMAP (0.3 g) was dissolved inmethylene chloride followed by addition of bromacetyl chloride (1 mL; 12mmol). After stirring for 18 h the reaction mixture was washed withaqueous Na₂CO₃ (2M) and HCl (1M), dried, concentrated and purified byflash chromatography using petroleum ether:methylene chloride (50:50) togive 1.8g (72%) of the sub-title compound.

[0451] (ii) Cyclooctyl-OOCCH₂—(R)Cgl-Aze-Pab-Z

[0452] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z×2HCl (703 mg; 1.2mmol) and cyclooctyl bromoacetate (363 mg; 1.46 mmol; from step (i)above). Yield 379 mg (46%).

[0453] FAB-MS:(m+1)=674(m/z)

Example 31 tBuCH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0454] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z×2HCl (2.5 g; 4.3mmol) and tertbutylmetyl bromoacetate (1.08 g; 5.2 mmol). Yield 1.87 g(69%).

[0455] FAB-MS:(m+1)=634 (m/z)

Example 32 (2-Me)BnOOCCH₂—(R)Cgl-Aze-Pab-Z

[0456] (i) Methylbenzyl bromoacetate

[0457] The sub-title compound was prepared analogously to the proceduredescribed in Example 30(i) from 2-methylbenzylalcohol (5 g; 41 mmol) andbromacetyl chloride (12.6 g; 80 mmol). Yield 8.2 g (82%).

[0458] (ii) (2-Me)BnOOCCH₂-(R)Cgl-Aze-Pab-Z

[0459] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z×2HCl (580 mg; 1mmol) and 2-methylbenzyl bromoacetate (290 mg; 1.2 mmol; from step (i)above). Yield 30 mg (4.5%).

[0460] LC-MS:(m+1)=668 (m/z)

Example 33 ChCH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0461] A solution of BnOOCCH₂—(R)Cgl-Aze-Pab-Z (1.41 g; 1.7 mmol) andcyclohexyl methylalcohol (6 mL) in triethylamine (474 μL) and methylenechloride (3 mL) was refluxed for 4 days. The reaction mixture was workedup to give a crude product which was purified by flash chromatographyusing methylene chloride:methanol (95:5) as eluent to give 801 mg (71%)of the title compound.

[0462] FAB-MS:(m+1)=660 (m/z)

Example 34 ChOOCH₃—(R)Cgl-Aze-Pab-Z

[0463] (i) Cyclohexyl bromoacetate

[0464] The sub-title compound was prepared analogously to the proceduredescribed in Example 32(i) above from cyclohexanol (1 g; 10 mmol) andbromacetylchioride (1 mL; 12 mmol).

[0465] (ii) ChOOCCH₂—(R)Cgl-Aze-Pab-Z

[0466] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z×2HCl (2.5 g; 4.32mmol) and cyclohexyl bromoacetate (1.5 g; 5.2 mmol). Yield 1.7 g (60%).

[0467] FAB-MS:(m+1)=646 (m/z)

Example 35 PhC(Me)₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0468] (i) 2-Phenyl-2-propyl bromoacetate

[0469] The sub-title compound was prepared analogously to the proceduredescribed in Example 30(i) from 2-phenyl-2-propanol (3 g; 22 mmol) andbromacetylchloride (4.16 g, 26 mmol). Yield 1.2 g (44%).

[0470] (ii) PhC(Me)₂OCCH₂—(R)Cgl-Aze-Pab-Z

[0471] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z×2HCl (1.2 g; 2.2mmol) and 2-phenyl-2-propyl bromoacetate (640 mg; 2.5 mmol; from step(i) above). Yield 1.3 g (86%).

[0472]¹H-NMR (500 MHz; CDCl₃) δ 9.3 (br s, 1H), 8.35 (t, 1H), 7.75 (d,2H), 7.45 (d, 2H), 7.30-7.05 (m, 10H or 11H), 5.15 (s, 2H), 4.78 (t,1H), 4.40-4.30 (AB part of ABX spectrum, 2H), 3.95 (q, 1H), 3.74 (q,1H), 3.27-3.19 (AB-spectrum, 2H), 2.72 (d, 1H), 2.43 (q, 2H), 1.93 (brd, 1H), 1.75-1.60 (m, 9H or 10H), 1.54 (d, 1H), 1.49-1.40 (m, 1H),1.25-1.0 (m, 4H), 0.92 (q, 1H)

Example 36 MeNHCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0473] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z×2HCl (1.0 g; 1.7mmol) and MeNHCOCH₂OOCCH₂Br (440 mg; 2 mmol; prepared analogously to theprocedures described in Example 11 above (steps (i), (ii) and (iii))using methylamine instead of cyclohexylamine). Yield 380 mg (35%).

[0474] FAB-MS:(m+1)=635 (m/z)

Example 37 tBuOOCCH₂—(R)Cgl-Aze-Pab-Z

[0475] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z×2HCl (500 mg; 1.0mmol) and t-butyl bromoacetate (231 mg; 1.2 mmol). Yield 420 mg (69%).

[0476] LC-MS:(m+1)=620 (m/z)

Example 38 (Me)₂CHC(Me)₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0477] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z (787 mg; 1.4 mmol)and 2,3-dimethyl-2-butyl bromoacetate (364 mg; 1.63 mmol). Yield 590 mg(67%).

[0478] FAB-MS:(m+1)=648(m/z)

Example 39

[0479] iPrOOCCH₂—(R)Cgl-Aze-Pab-Z

[0480] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z (700 mg; 1.2 mmol)and isopropyl bromoacetate (262 mg; 1.5 mmol). Yield 225 mg (31%)

[0481] FAB-MS: (m+1)=606(m/z)

Example 40 BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe)

[0482] (i) Boc-(R)Cgl-Aze-Pab-COOPh(4-OMe)

[0483] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(i) from Boc-(R)Cgl-Aze-Pab-H and 4-methoxyphenylchloroformate.

[0484] FAB-MS:(m+1)=622(m/z)

[0485] (ii) H—(R)Cgl-Aze-Pab-COOPh(4-OMe)×2HCl

[0486] The sub-title compound was prepared analogously to the proceduredescribed in Example 4(ii) from Boc-(R)Cgl-Aze-Pab-COOPh(4-OMe) (fromstep (i) above).

[0487] (iii) BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe)

[0488] The title compound was prepared analogously to the proceduredescribed in Example 1 (iii) from H—(R)Cgl-Aze-Pab-COOPh(4-OMe)×2HCl (85mg; 0.16 mmol; from step (iii) above) and benzyl bromoacetate (90 mg;0.2 mmol). Yield 60 mg (56%).

[0489] FAB-MS:(m+1)=670 (m/z)

Example 41 ChCH₂OOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe)

[0490] The title compound was prepared analogously to the proceduredescribed in Example 1 (iii) from H—(R)Cgl-Aze-Pab-COOPh(4-OMe) (554 mg;0.64 mmol; see Example 40(ii) above) and cyclohexylmethyl bromoacetate(165 mg; 0.7 mmol). Yield 34 mg (8%).

[0491] FAB-MS:(m+1)=676 (m/z)

Example 42 (2-Me)BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe)

[0492] The title compound was prepared analogously to the proceduredescribed in Example 1(ii) from H—(R)Cgl-Aze-Pab-COOPh(4-OMe) (522 mg; 1mmol; see Example 40(ii) above) and 2-(methyl)benzyl bromoacetate (365mg; 1.5 mmol). Yield 158 mg (23%).

[0493] LC-MS:(m+1)=684 (m/z)

Example 43 EtOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-Me)

[0494] (i) Boc-(R)Cgl-Aze-Pab-COOPh(4-Me)

[0495] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(i) from Boc-(R)Cgl-Aze-Pab (1.96 g; 4.56 mmol)and 4-tolyl-chloroformate (850 mg; 4.99 mmol). Yield 1.39 g (55%).

[0496] FAB-MS:(m+1)=606(m/z)

[0497] (ii) H—(R)Cgl-Aze-Pab-COOPh(4-Me)

[0498] The sub-title compound was prepared analogously to the proceduredescribed in Example 4(ii) from Boc-(R)Cgl-Aze-Pab-COOPh(4-Me) (388 mg;0.64 mmol; from step (i) above). Yield 293 mg (91%).

[0499] FAB-MS:(m+1)=506(m/z)

[0500] (iii) EtOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-Me)

[0501] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOPh(4-Me) (288 mg;0.6 mmol; from step (ii) above) and ethyl bromoacetate (114 mg; 0.7mmol). Yield 81 mg (24%).

[0502] FAB-MS:(m+1)=592 (m/z)

Example 44 BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-Me)

[0503] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOPh(4-Me) (272 mg;0.54 mmol; see Example 43(ii) above) and benzyl bromoacetate (147 mg;0.6 mmol). Yield 107 mg (31%).

[0504] FAB-MS:(m+1)=654(m/z)

Example 45 BnOOCCH₂—(R)Cgl-Aze-Pab-COO-nBu

[0505] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-nBu×2HCl (400 mg;0.74 mmol; see Example 9(ii) above) and benzyl bromoacetate (210 mg;0.88 mmol). Yield 220 mg (48%).

[0506] FAB-MS:(m+1)=620 (m/z)

Example 46 iPrOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂

[0507] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂×2TFA (456mg; 0.67 mmol; see Example 1(ii) above) and isopropyl bromoacetate (145mg; 0.8 mmol). Yield 294 mg (79%).

[0508] FAB-MS:(m+1)=556 (m/z)

Example 47 EtOOCCH₂—(R)Cgl-Aze-Pab-COO-iBu

[0509] (i) Boc-Pab-COO-iBu

[0510] To a solution of Boc-Pab-H (50 mg; 2.0 mmol; prepared from Pab-Zand (Boc)2O (forming Boc-Pab-Z), followed by hydrogenation over Pd/C)and triethylamine (400 mg; 4.0 mmol) in methylene chloride (10 mL) wasadded i-butyl chloroformate (270 mg; 2.2 mmol) at 0° C. After stirringfor 5 h, water was added. The organic phase was dried (Na₂SO₄) andconcentrated to give 530 mg (76%) of the sub-title compound.

[0511]¹H-NMR (500 MHz, CDCl₃) δ 9.5 (bs, 1H), 7.82 (d, 2H), 7.31 (d,2H), 6.6 (bs, 1H), 5.0 (bs, 1H), 4.33 (bd, 2H), 3.93 (d, 2H), 2.04 (m,1H), 1.45 (s, 9H), 0.97 (d, 6H)

[0512] (ii) H-Pab-COO-iBu×2HCl

[0513] The sub-title compound was prepared analogously to the procedureto described in Example 4(ii) from Boc-Pab-COO-iBu (520 mg; 1.5 mmol;from step (i) above). Yield 430 mg (88%).

[0514]¹H-NMR (500 MHz, MeOD) δ 7.89 (d, 2H), 7.75 (d, 2H), 4.30 (s, 2H),4.17 (d, 2H), 2.11-2.05 (m, 1H), 1.02 (d, 6H)

[0515] (iii) Boc-(R)Cgl-Aze-Pab-COO-iBu

[0516] To a solution of Boc-(R)Cgl-Aze-OH (480 mg; 1.4 mmol),H-Pab-COO-iBu×2HCl (430 mg; 1.3 mmol; from step (ii) above) and DMAP(650 mg; 5.3 mmol) in acetonitrile (20 mL) was added EDC (270 mg; 1.4mmol). After stirring for 3 days at room temperature the reactionmixture was concentrated and then dissolved in water and EtOAc. Theorganic phase was washed with NaHCO₃ (aq) and dried (Na₂SO₄),concentrated and purified by flash chromatography using EtOAc as eluentto give 510 mg (52%) of the sub-title compound.

[0517] (iv) H—(R)Cgl-Aze-Pab-COO-iBu×2HCl

[0518] The sub-title compound was prepared analogously to the proceduredescribed in Example 4(ii) from Boc-(R)Cgl-Aze-Pab-COO-iBu (500 mg; 0.88mmol; from step (iii) above). Yield 360 mg (87%).

[0519] (v) EtOOCCH₂—(R)Cgl-Aze-Pab-COO-iBu

[0520] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-iBu×2HCl (290 mg;0.53 mmol; from step (iv) above) and ethyl bromoacetate (110 mg; 0.64mmol). Yield 140 mg (47%).

[0521] FAB-MS:(m+1)=558 (m/z)

Example 48 BnOOCCH₂—(R)Cgl-Aze-Pab-COO-nPr

[0522] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-nPr×2TFA (902 mg;1.3 mmol; see Example 5(ii) above) and benzyl bromoacetate (362 mg; 1.6mmol). Yield 199 mg (25%).

[0523]¹H-NMR: (400 MHz; CDCl₃) δ 8.43 (bs, 1H), 7.78 (d, 2H), 7.38-7.27(m, 7H), 5.05 (s, 2H), 4.90 (dd, 1H), 4.56-4.39 (AB part of ABXspectrum, 2H), 4.12-4.03 (m, 3H), 3.98-3.91 (q, 1H), 3.33-3.22(AB-spectrum, 2H), 2.85 (d, 1H), 2.65-0.94 (m, 19H)

Example 49 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCCh

[0524] (i) EtSCOOCH₂OOCCh

[0525] To a solution of tetrabutylammonium hydrogensulphate (15.6 g,45.6 mmol) and cyclohexane carboxylic acid (5.85 g, 46 mmol) inmethylene chloride was added NaOH (9.1 mL, 10M; 68 mmol) at 0° C. Afterstirring for 5 minutes the reaction mixture was filtered, washed withmethylene chloride, dissolved in toluene, concentrated and dissolved inTHF to give [Bu₄N]⁺[OOCCh]⁻. EtSCOOCH₂Cl (4 g; 25.9 mmol; see Folkmannand Lund, J. Synthesis, (1990), 1159) was added to the THF solution of[Bu₄N]⁺[OOCCh]⁻ at room temperature. After stirring at room temperaturefor 12 h the reaction mixture was concentrated and purified by flashchromatography to give 2.57 g (40%) of the subtitle compound.

[0526]¹H-NMR (400 MHz, CDCl₃) diagnostic peaks a 5.80 (s, 2H, O—CH₂—O),2.85 (q, 2H, CH₂—S)

[0527] (ii) ClCOOCH₂OOCCh

[0528] To EtSCOOCH₂OOCCh (2.9 g; 11.8 mmol; from step (i) above) wasadded dropwise SO₂Cl₂ (3.18 g; 23.6 mmol) at 0° C. After stirring for 30minutes the reaction mixture was concentrated to give 1.82 g (70%) ofthe desired compound.

[0529]¹H-NMR (500 MHz, CDCl₃) diagnostic peaks δ 5.82 (s, 2H, O—CH₂—O)

[0530] (iii) Boc-(R)Cgl-Aze-Pab-COOCHO₂OOCCh

[0531] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(i) from Boc-(R)Cgl-Aze-Pab-H (750 mg; 1.59 mmol)and ClCOOCH₂OOCCh (460 mg; 2.1 mmol; from step (ii) above). The crudeproduct was purified by preparative RPLC. Yield 355 mg (9%).

[0532] FAB-MS:(m+1)=656(m/z)

[0533] (iv) H—(R)Cgl-Aze-Pab-COOCH₂OOCCh×2TFA

[0534] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(ii) from Boc-(R)Cgl-Aze-Pab-COOCH₂OOCCh (fromstep (iii) above).

[0535] (v) EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCCh

[0536] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOCH₂OOCCh×2TFA (193mg; 0.35 mmol; from step (iv) above) and ethyl trifluoroacetate (83 mg;0.35 mmol). Yield 87 mg (39%).

[0537]¹H-NMR (400 MHz, CDCl) δ 8.48 (t br, 1H), 7.83 (d, 2H), 7.37 (d,2H), 5.86 (s, 2H), 4.95 (dd, 1H), 4.15-4.39 (AB part of ABX spectrum,2H), 4.18-4.05 (m, 5H), 3.26-3.17 (AB-spectrum, 2H), 2.87 (d, 1H),2.75-0.95 (m, 29H)

Example 50 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCCH₂Ch

[0538] The title compound was prepared analogously to the proceduredescribed in Example 49 above starting with cyclohexyl acetic acidinstead of cyclohexane carboxylic acid. Yield 74 mg (17%).

[0539] FAB-MS: (m+1)=656(m/z)

Example 51 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH(Me)OOCPh

[0540] The title compound was prepared analogously to the proceduredescribed in Example 49 above starting with EtSCOOCH(CH₃)Cl (preparedfrom ClCOCH(CH₃)Cl and EtSH using the procedure described by Folkmann etal in J. Synthesis, (1990), 1159) instead of EtSCOOCH₂Cl. Yield 70 mg(23%).

[0541] FAB-MS:(m+1)=650 (m/z)

Example 52 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCPh

[0542] The title compound was prepared analogously to the proceduredescribed in Example 49 above using benzoic acid instead of cyclohexanecarboxylic acid. Yield 50 mg (39%).

[0543]¹H-NMR (300 MHz, CDCl₃) δ 9.73-9.25 (s br, 1H), 8.45 (t, 1H), 8.05(d, 2H), 7.83 (d, 2H), 7.60-7.10 (m, 6H), 6.10 (s, 2H), 4.96-4.84 (dd,1H), 4.62-4.30 (ABX, 2H), 4.20-3.93 (m, 4H), 3.25 (s, 2H), 2.84 (d, 1H),2.73-2.41 (m, 2H), 2.41-0.87 (m, 15H)

[0544]¹³C-NMR (300 MHz, CDCl₃, amidine and carbonyl carbons) δ 163.1,165.3, 169.0, 170.8, 172.3, 175.5

Example 53 BnOOCCH₂—(R)Cgl-Aze-Pab-COOCH(Me)OAc

[0545] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOCH(CH₃)OC(O)CH₃(108 mg; 0.21 mmol; see Example 14(ii) above) and benzyl bromoacetate(36 μL; 0.23 mmol). Yield 41 mg (30%).

[0546] FAB-MS:(m+1)=650(m/z)

Example 54 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OAc

[0547] (i) H—(R)Cgl-Aze-Pab-COOCH₂OAc×2TFA

[0548] The sub-title compound was prepared analogously to the proceduredescribed in Example 14 (steps (i) and (ii)) above using acetoxymethyl4-nitrophenylcarbonate (prepared analogously to the method described inExample 12(iii) using silver acetate instead of silver pivalate). Workup gave the sub-title compound which was used in the next step withoutfurther purification.

[0549] (ii) EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OAc

[0550] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) above from H—(R)Cgl-Aze-Pab-COOCH₂OAc×2TFA(0.83 mmol; from step (i) above) and ethyl bromoacetate (2.2 mmol).Yield 286 mg.

[0551] FAB-MS:(m+1)=574 (m/z)

Example 55 tBuOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OAc

[0552] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) above from H—(R)Cgl-Aze-Pab-COOCH₂OAc×2TFA(0.313 mmol; see Example 54(i) above) and t-butyl bromoacetate (73 mg;0.376 mmol). Yield 156 mg (83%).

[0553] FAB-MS:(m+1)=602(m/z)

Example 56 BnOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOC-tBu

[0554] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOCH₂OOC-tBu (379 mg;0.71 mmol; see Example 12(v) above) and benzyl bromoacetate (135 μL;0.85 mmol). Yield 146 mg (30%).

[0555] FAB-MS:(m+1)=678(m/z)

Example 57 EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CCl₃

[0556] (i) Boc-(R)Cgl-Aze-Pab-COOCH₂CCl₃

[0557] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(i) from Boc-(R)Cgl-Aze-Pab-H (1.0 g; 2.12 mmol),2M NaOH (11.7 ml) and trichloroethyl chloroformate (494 mg; 2.33 mmol).Yield 1.08 g (79%).

[0558] (ii) H—(R)Cel-Aze-Pab-COOCH₂CCl₃

[0559] The sub-title compound was prepared analougously to the proceduredescribed in Example 1(ii) from Boc-(R)Cgl-Aze-Pab-COOCH₂CCl₃ (1.04 g;1.607 mmol; from step (i) above). Yield 1.43 g (99%).

[0560]¹H-NMR: (500MHz; CD₃OD) δ 7.79 (d, 2H), 7.61 (d, 2H), 5.10 (s,2H), 4.87-4.81 (m, 2H), 4.63-4.52 (q, 2H), 4.41-4.34 (m, 1H), 4.30-4.24(m, 1H), 3.72 (d, 1H), 2.72-2.63 (m, 1H), 2.32-2.25 (m, 1H), 1.88-1.10(m, 14H)

[0561] (iii) EtOOCCH₂—(R)Cgl-Aze Pab-COOCH₂CCl₃

[0562] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOCH₂CCl₃ (400 mg;0.52 mmol; from step (ii) above) and ethyl bromoacetate (95 mg; 0.57mmol). Yield 8 mg (23%).

[0563]¹H-NMR: (500MHz; CDCl₃) δ 8.47 (bt, 1H), 7.83 (d, 2H), 7.48 (bs,1H), 7.31 (d, 2H), 4.92 (dd, 1H), 4.85 (s, 2H), 4.58-4.39 (AB part ofABX spectrum, 2H), 4.16-4.06 (m, 4H), 3.24 (s, 2H), 4.87 (d, 1H),2.65-2.59 (m, 1H), 2.5-2.48 (m, 1H), 2.10-0.95 (m, 16H)

Example 58 MeOOC—C(═CEt)CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0564] (i) MeOOC—C(═CH)C(OH)Et

[0565] Propionaldehyde (10.1 g; 0.174 mol) was added dropwise to asolution of methyl acrylate (10 g; 0.116mol) and1,4-diazobicyclo[2,2,2]octane (1.3 g; 0.0116 mol). The reaction mixturewas stirred at room temperature for 14 days. Ethyl acetate (150 ml) wasadded. The organic phase was washed with water and brine, dried(Na₂SO₄), filtered and concentrated to give the desired compound. Yield15.5 g (93%).

[0566]¹H-NMR: (400MHz; CDCl₃) δ 6.24 (s, 1H), 5.81 (s, 1H), 4.34 (t,1H), 3.78 (s, 3H), 2.82 (bs, 1H), 1.69 (m, 2H), 0.95 (t, 3H)

[0567] (ii) MeOOC—C(═CEt)CH₂Br

[0568] HBr (6.5 ml, ˜48%) was added dropwise to MeOOC—C(═CH)C(OH)Et (3g; 20.8 mmol; from step (i) above) at 0° C. After 5 minutes H₂SO₄(conc.; 6 ml) was added dropwise. The reaction mixture was stirred for12 hours at room temperature. Two phases was separated and the top phasewas diluted with ether. The ether phase was washed with water andaqueous NaHCO₃, dried (Na₂SO₄ and charcoal) and concentrated. Theresidue was purified by flash chromatography. Yield 1.7 g (40%).

[0569]¹H-NMR: (400 MHz; CDCl₃) δ 6.97 (t, 3H), 4.23 (s, 2H), 3.8 (s,3H), 2.32 (m, 2H), 1.13 (t, 3H)

[0570] (iii) tBuOOCCH₂—(R)Cgl-Aze-Pab-Z

[0571] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z (2.1 g; 3.6 mmol)and t-butyl bromoacetate (780 mg; 4.0 mmol). Yield 1.73 g (78%).

[0572] (iv) HOOCCH₂—(R)Cgl-Aze-Pab-Z

[0573] A solution of tBuOOCCH₂—(R)Cgl-Aze-Pab-Z (from step (iii) above)and TFA in methylene chloride was stirred in room temperature for 3 h.The rection mixture was concentrated and freeze dried from water and HCl(conc.; 10 eq.).

[0574] (v) MeOOC—C(═CEt)CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0575] A solution of HOOCCH₂—(R)Cgl-Aze-Pab-Z (263 mg; 0.41 mmol; fromstep (iv) above), NaOH (1M; 1.239 ml; 1.239 mmol) and water (4 ml) wasfreeze dried. DMF (5 ml) was added, followed by dropwise addition ofMe—OOC—C(═CEt)CH₂Br (103 mg; 0.496 mmol; from step (ii) above) at 0° C.The reaction mixture was stirred for 24 h at room temperature, dilutedwith toluene (5 ml), washed with water, dried (Na₂SO₄) and concentrated.The residue was purified by flash chromatography using EtOAc:methanol(95:5) as eluent. Yield 95 mg (33%).

[0576] FAB-MS:(m+1)=690 (m/z)

Example 59 MenOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe)

[0577] (i) MenOOCCH₂Br

[0578] The sub-title compound was prepared analogously to the proceduredescribed in Example 30(i) above from MenOH (10 mmol) and bromoacetylchloride (12 mmol). Yield 1.5 g (54%).

[0579] (ii) MenOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe)

[0580] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-Ph(4-OMe) (521 mg;1 mmol; see Example 40(ii) above) and MenOOCCH₂Br (416 mg; 1.5 mmol;from step (i) above). Yield 36 mg (5%).

[0581] FAB-MS:(m+1)=718 (m/z)

Example 60 tBuOOCCH₂—(R)Cgl-Aze-Pab-COOnPr

[0582] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-nPr (575 mg; 0.837mmol; see Example 5(ii) above) and t-butyl bromoacetate (196 mg; 1.01mmol). Yield 110 mg (23%).

[0583] LC-MS:(m+1)=572 (m/z)

Example 61 MenOOCCH₂—(R)Cgl-Aze-Pab-Z

[0584] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z (0.7 g; 1.21 mmol)and MenOOCCH₂Br (0.4 g; 1.45 mmol; see Example 59(i) above). Yield 0.33g (38%).

[0585] FAB-MS:(m+1)=702 (m/z)

Example 62 BnOOCCH₂—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂)

[0586] (i) Boc-(R)Cgl-Aze-Pab-COO-Bn(4-NO₂)

[0587] The sub-title compound was prepared analogously to the proceduredescribed in Example 1(i) from Boc-(R)Cgl-Aze-Pab-H (1.03 g; 2.18 mmol),2M NaOH (24 mL) and 4-NO₂-benzyl chloroformate (518 mg; 2.4 mmol). Yield1.32 g (93%).

[0588] FAB-MS:(m+1)=651 (m/z)

[0589] (ii) H—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂)

[0590] The sub-title compound was prepared analogously to the proceduredescribed in Example 4(ii) from Boc-(R)Cgl-Aze-Pab-COO-Bn(4-NO₂) (1.32mg; 2.03 mmol; from step (i) above). Yield 1.0 g (79%).

[0591] FAB-MS:(m+1)=551 (m/z)

[0592] (iii) BnOOCCH₂—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂)

[0593] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂) (0.5 g;0.80 mmol; from step (ii) above) and benzyl bromoacetate (220 mg; 0.90mmol).

[0594] FAB-MS: (m+1)=699 (m/z)

Example 63 EtOOCCH₂—(R)Cgl-Aze-Pab-Bn(4-NO₂)

[0595] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂) (211 mg;0.38 mmol; see Example 62(ii) above) and ethyl bromoacetate (47 μl; 0.42mmol). Yield 44 mg (18%).

[0596]¹H-NMR: (300MHz; CDCl3) δ 9.55 (s, 1H), 8.50 (bt, 1H), 8.20 (d,2H), 7.80 (d, 2H), 7.60 (d, 2H), 7.35 (d, 2H), 6.87 (bs, 1H), 4.95 (dd,1H), 4.65-4.40 (AB part of ABX spectrum, 2H), 4.18-4.04 (m, 5H),3.27-3.15 (AB-spectrum, 2H), 2.87 (d, 1H), 2.75-2.60 (m, 1H), 2.57-2.45(m, 1H), 2.00-0.95 (m, 16H).

Example 64 PrlC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0597] (i) PrlC(O)CH₂OH

[0598] A mixture of 2,5-dioxo-1,4-dioxane (2.0 g; 17 mmol) andpyrrolidine (8 ml; 97 mmol) was refluxed for 1 h. The excess pyrrolidinewas removed by evaporation. Yield 4.4 g (99%).

[0599] FAB-MS(m+1)=130 (m/z)

[0600] (ii) PrlC(O)CH₂OOCCH₂Br

[0601] To a solution of PrlC(O)CH₂OH (0.4 g; 3.1 mmol; from step (i)above) in DMF (15 ml) was added dropwise bromoacetyl bromide (0.63 g;3.1 mmol) at 0° C. The reaction mixture was stirred for 1.5 h at 0° C.and 3 h at room temperature. Additional bromoacetyl bromide (0.63 g; 3.1mmol) was added and the reaction mixture was heated to 80° C., stirredat room temperature for 12 h and concentrated. Yield 320 mg (41%)

[0602] FAB-MS(m+1)=252 (m/z)

[0603] (iii) PrlC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z

[0604] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-Z (580 mg; 1 mmol) andPrlC(O)CH₂OOCCH₂Br (300 mg; 1.2 mmol; from step (ii) above). Yield 400mg (60%).

[0605] FAB-MS(m+1)=675 (m/z)

[0606]¹H-NMR: (500MHz; CDCl3) δ 9.66-9.42 (bs, 1H), 8.64-8.56 (m, 1H),8.03-7.93 (d, 2H), 7.89-7.66 (bs, 1H), 7.45 (d, 2H), 7.45-7.25 (m, 5H),5.20 (s, 2H), 4.98-4.92 (dd, 1H), 4.82-4.74 (m, 1H), 4.62, 4.58 (ABspectrum, 2H), 4.26-4.05 (m, 3H),3.47-3.16 (m, 6H), 2.95 (d, 1H),2.78-2.68 (m, 1H), 2.54-2.42 (m, 1H), 2.03-1.95 (m, 16H)

Example 65 (2-Me)BnOOCCH₂—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂)

[0607] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂) (500 mg;0.80 mmol; see Example 62(ii) above) and 2-(methyl)benzyl bromoacetate(234 mg; 0.96 mmol; see Example 32(i) above). Yield 528 mg (92%).

[0608]¹H-NMR: (400 MHz, CDCl₃) δ 9.34 (bs, 1H), 8.38 (t, 1H), 8.09 (d,2H), 7.72 (d, 2H), 7.48 (d, 2H), 7.37 (bs, 1H), 7.23 (d, 2H), 7.17-7.05(m, 4H), 5.18 (s, 2H), 5.00 (s, 2H), 4.81 (dd, 1H), 4.45-4.34 (AB partof ABX spectrum, 2H), 4.04-3.97 (q, 1H), 3.93-3.86 (q, 1H), 3.27-3.17(AB spectrum, 2H), 2.79 (d, 1H), 2.54-2.35 (m,2H), 2.22 (s, 3H),1.91-1.84 (bd, 1H),1.71-1.39 (m, 5H), 1.19-0.84 (m, 4H).

Example 66 MeOOCCH₂—(R)Cgl-Aze-Pab-COOEt

[0609] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOEt (305 mg; 0.69mmol; see Example 4(ii) and methyl bromoacetate (126 mg; 0.83 mmol).Yield 188 mg (53%).

[0610] LC-MS:(m+1)=516(m/z)

Example 67 (nPr)₂NC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂)

[0611] (i) (nPr)₂NC(O)CH₂OOCCH₂Cl

[0612] A mixture of (nPr)₂NC(O)CH₂OH (244 mg; 1.53 mmol; see Example12(i) above) and bromacetyl chloride (270 mg; 1.72 mmol) was stirred atroom temperature for 12 hours. The mnixture was poured into aqueousNaHCO₃ and extracted with methylene chloride. The organic phase waswashed with aqueous KHSO₄ (0.2M) and brine, dried and concentrated.

[0613] FAB-MS:(m+1)=237(m/z)

[0614]¹H-NMR: (400MHz, CDCl₃) δ 4.82 (s, 2H), 4.22 (s, 2H, 3.31-3.26 (t,2H), 3.10-3.15 (t, 2H), 1.68-1.52 (m, 2H), 1.97-0.86 (m, 6H)

[0615] (ii) (nPr)₂NC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-COO-Bn(4-NO₂)

[0616] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOBn(4-NO₂) (343 mg;0.62 mmol; see Example 62(ii) above) and (nPr)₂NC(O)CH₂OOCCH₂Cl (160 mg;0.68 mmol; from step (i) above). Yield 89 mg (19%).

[0617] FAB-MS: (m+1)=750(m/z)

Example 68 (2-Me)BnOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCtBu

[0618] The title compound was prepared analogously to the proceduredescribed in Example 1(iii) from H—(R)Cgl-Aze-Pab-COOCH₂OOCtBu (380 mg;0.71 mmol; see Example 12(v) above) and 2-(methyl)benzyl bromoacetate(215 mg; 0.88 mmol; see Example 32(i) above). Yield 37 mg (7.5%).

[0619] FAB-MS:(m+1)=692(m/z)

Example 69

[0620] The compounds of Examples 1 to 68 were all tested in Test A aboveand were all found to exhibit an IC₅₀TT value of more than 1.0 μM (iethey were are inactive to thrombin per se; cf. the active inhibitorHOOC—CH₂—(R)Cgl-Aze-Pab-H which exhibits an IC₅₀TT of 0.01 μM).

Example 70

[0621] The compounds of Examples 1 to 68 were tested in one, two or allof Tests B, C and/or D above, and were all found to exhibit oral and/orparenteral bioavailability in the rat as the active inhibitorHOOC—CH₂—(R)Cgl-Aze-Pab-H, either as the free acid and/or as one or moreester thereof. Based on the assumption that HOOC—CH₂—(R)Cgl-Aze-Pab-H isformed in the rat, the bioavailability was calculated according to theformulae described in Test B and/or Test C as appropriate.

[0622] Abbreviations Ac = acetyl aq = aqueous Aze =S-Azetidine-2-carboxylic acid Boc = t-butyloxycarbonyl (Boc)₂O =di-t-butyldicarbonate Bn = benzyl Bu = butyl Cgl = cyclohexylglycine Ch= cyclohexyl DCC = dicyclohexyl carbodiimide DMAP = N,N-dimethyl aminopyridine EDC = 1-(3-dimethylaminopropyl)-3-ethylcarbodiimidehydrochloride Et = ethyl EtOH = ethanol EtOAc = ethyl acetate h = hoursHCl = hydrochloric acid H-Pab-H = 1-amidino-4-aminomethyl benzeneH-Pab-Z = 4-aminomethyl-1-(N-benzyloxycarbonylamidino) benzene HPLC =high performance liquid chromatography K₂CO₃ = anhydrous potassiumcarbonate Me = methyl Men = (1R,2S,5R)-menthyl Pab-OH =4-aminomethyl-benzamidoxime (4-aminomethyl-1- (amino-hydroxyiminomethyl)benzene Piv(aloyl) = 2,2-dimethylacetyl Pr = propyl Prl = N-pyrrolidinylRPLC = reverse phase high performace liquid chromatography TFA =trifluoroacetic acid THF = tetrahydrofuran Z = benzyloxy carbonyl

[0623] Prefixes n, s, i and t have their usual meanings: normal, iso,sec and tertiary. Prefixes in the NMR-spectra s, d, t, q, and b meansinglet, doublet, triplet, quartet, and broad, respectively. Thestereochemistry for the amino acids is by default (S) if not otherwisestated.

1. A compound of formula I, R¹O(O)C—CH₂—(R)Cgl-Aze-Pab-R₂   I wherein R¹represents —R³ or —A¹C(O)N(R⁴)R⁵ or —A¹C(O)OR⁴; A¹ represents C₁₋₅alkylene; R² (which replaces one of the hydrogen atoms in the amidinounit of Pab-H) represents OH, OC(O)R⁶, C(O)OR⁷ or C(O)OCH(R⁸C(O)R⁹; R³represents H, C₁₋₁₀ alkyl, or C₁₋₃ alkylphenyl (which latter group isoptionally substituted by C₁₋₆ alkyl, C₁₋₆ alkoxy, nitro or halogen); R⁴and R⁵ independently represent H, C₁₋₆ alkyl, phenyl, 2-naphthyl or,when R¹ represents -A¹C(O)N(R⁴)R⁵, together with the nitrogen atom towhich they are attached represent pyrrolidinyl or piperidinyl; R⁶represents C₁₋₁₇ alkyl, phenyl or 2-naphthyl (all of which areoptionally substituted by C₁₋₆ alkyl or halogen); R⁷ represents2-naphthyl, phenyl, C₁₋₃ alkylphenyl (which latter three groups areoptionally substituted by C₁₋₆ alkyl, C₁₋₆ alkoxy, nitro or halogen), orC₁₋₁₂ alkyl (which latter group is optionally substituted by C₁₋₆alkoxy, C₁₋₆acyloxy or halogen); R⁸ represents H or C₁₋₄ alkyl; and R⁹represents 2-naphthyl, phenyl, C₁₋₆ alkoxy or C₁₋₈ alkyl (which lattergroup is optionally substituted by halogen, C₁₋₆ alkoxy or C₁₋₆acyloxy); provided that when R¹ represents R³, R³ represents benzyl,methyl, ethyl, n-butyl or n-hexyl and R² represents C(O)OR⁷, then R⁷does not represent benzyl; or a pharmaceutically-acceptable saltthereof.
 2. A compound of formula I, as defined in claim 1, wherein A¹represents C₁₋₃ alkylene when R¹ represents -A¹C(O)N(R⁴)R⁵.
 3. Acompound of formula I, as defined in claim 1 or claim 2, wherein R⁴represents H or C₁₋₆ alkyl when R¹ represents -A¹C(O)N(R⁴)R⁵.
 4. Acompound of formula I, as defined in any one of claims 1 to 3, whereinR⁵ represents C₁₋₆ alkyl or C₄₋₆ cycloalkyl when R¹ represents-A¹C(O)N(R⁴)R⁵.
 5. A compound of formula I, as defined in any one ofclaims 1 to 3, wherein R⁴ and R⁵ together represent pyrrolidinyl when R¹represents -A¹C(O)N(R⁴)R⁵.
 6. A compound of formula I, as defined in anyone of claims 2 to 5, wherein A¹ represents C₁₋₃ alkylene, and R⁴represents H or C₁₋₃ alkyl and R⁵ represents C₂₋₆ alkyl or C₅₋₆cycloalkyl, or R⁴ and R⁵ together represent pyrrolidinyl.
 7. A compoundof formula I, as defined in claim 1, wherein A¹ represents C₁₋₅ alkylenewhen R¹ represents -A¹C(O)OR⁴.
 8. A compound of formula I, as defined inclaim 1 or claim 7, wherein R⁴ represents C₁₋₆ alkyl when R¹ represents-A¹C(O)OR⁴.
 9. A compound of formula I, as defined in claim 7 or claim8, wherein A¹ represents C₁₋₅ alkylene and R⁴ represents C¹⁻⁴ alkyl. 10.A compound of formula I, as defined in claim 1, wherein R³ represents H,C₁₋₁₀ alkyl (which latter group may be linear or, when there are asufficient number of carbon atoms, may be branched and/or be partiallycyclic or cyclic), or C₁₋₃ alkylphenyl (which latter groups isoptionally substituted, may be linear or, when there are a sufficientnumber of carbon atoms, be branched), when R¹ represents R³.
 11. Acompound as claimed in claim 1 or claim 10, wherein R¹ represents H,linear C₁₋₁₀ alkyl, branched C₃₋₁₀ alkyl, partially cyclic C₄₋₁₀ alkyl,C₄₋₁₀ cycloalkyl, optionally substituted linear C₁₋₃ alkylphenyl,optionally substituted branched C₃ alkylphenyl.
 12. A compound asclaimed in claim 11, wherein R¹ represents linear C₁₋₆ alkyl, C₆₋₁₀cycloalkyl, or optionally substituted linear C₁₋₃ alklphenyl.
 13. Acompound of formula I, as defined in any one of claims 1 to 12, whereinR² represents OH.
 14. A compound of formula I, as defined in any one ofclaims 1 to 12, wherein R⁶ represents optionally substituted phenyl orC₁₋₁₇ alkyl (which latter group may be linear or, when there are asufficient number of carbon atoms, may be branched, be cyclic orpartially cyclic, and/or be saturated or unsaturated) when R² representsOC(O)R⁶.
 15. A compound as claimed in claim 14 wherein R⁶ representsoptionally substituted phenyl, linear C₁₋₄ alkyl, branched C₃₋₄ alkyl orcis-oleyl.
 16. A compound as claimed in claim 15 wherein R⁶ representslinear C₁₋₃ alkyl or branched C₃ alkyl.
 17. A compound of formula I, asdefined in any one of claims 1 to 12, wherein R⁷ represents optionallysubstituted phenyl, C₁₋₁₂ alkyl (which latter group is optionallysubstituted, may be linear or, when there are a sufficient number ofcarbon atoms, may be branched, cyclic or partially cyclic, and/orsaturated or unsaturated), or C₁₋₃ alkylphenyl (which latter group isoptionally substituted, may be linear or, when there are a sufficientnumber of carbon atoms, may be branched) when R² represents C(O)OR⁷. 18.A compound as claimed in claim 17 wherein R⁷ represents optionallysubstituted and/or optionally unsaturated linear C₁₋₄ alkyl oroptionally substituted and/or optionally unsaturated branched C₃₋₄alkyl, optionally substituted phenyl, or optionally substituted linearC₁₋₃ alkylphenyl or optionally substituted branched C₃ alkylphenyl. 19.A compound as claimed in claim 18 wherein R⁷ represents optionallysubstituted linear C₁₋₄ alkyl or optionally substituted branched C₃₋₄alkyl, optionally substituted linear C₁₋₃ alkylphenyl or branched C₃alkylphenyl.
 20. A compound of formula I, as defined in any one ofclaims 1 to 12, wherein R⁸ represents H or methyl, when R² representsC(O)OCH(R⁸)OC(O)R⁹.
 21. A compound of formula I, as defined in any oneof claims 1 to 12 or claim 20, wherein R⁹ represents phenyl, or C₁₋₈alkyl (which latter group is optionally substituted, may be linear or,when there are a sufficient number of carbon atoms, may be branchedand/or cyclic or partially cyclic) when R² represents C(O)OCH(R⁸OC(O)R⁹.22. A compound of formula I, as defined in claim 20 or claim 21 whereinR⁸ represents H or methyl and R⁹ represents phenyl, C₅₋₇ cycloalkyl,linear C₁₋₆ alkyl, branched C₃₋₆ alkyl or partially cyclic C₇₋₈ alkyl.23. A compound as claimed in claim 22 wherein R⁸ represents H and R⁹represents C₅₋₇ cycloalkyl, linear C₁₋₆ alkyl or partially cyclic C₇₋₈alkyl.
 24. A compound as claimed in any one of the preceeding claimswherein, when R¹ represents R³ and R³ represents optionally substitutedC₁₋₃ alkylphenyl, the optional substituent C₁₋₆ alkyl.
 25. A compound asclaimed in claim 24 wherein the substituent is methyl.
 26. A compound asclaimed in any one of the preceeding claims wherein, when R² representsC(O)OR⁷ and R⁷ represents optionally subsituted C₁₋₁₂ alkyl, theoptional substituent is selected from halogen and C₁₋₆ alkoxy.
 27. Acompound as claimed in claim 26 wherein the substituent is selected fromchloro and methoxy.
 28. A compound as claimed in any one of thepreceeding claims wherein, when R² represents C(O)OR⁷ and R⁷ representsoptionally subsituted phenyl, the optional substituent is selected fromC₁₋₆ alkyl, C₁₋₆ alkoxy and halogen.
 29. A compound as claimed in claim28 wherein the substituent is selected from methyl, methoxy and chloro.30. A compound as claimed in any one of the preceeding claims whereinwhen R² represents C(O)OR⁷ and R⁷ represents optionally subsituted C₁₋₃alkylphenyl, the optional substituent is nitro.
 31. A compound asclaimed in claim 1 which is EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂;nPrOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂;tBuOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂; EtOOCCH₂—(R)Cgl-Aze-Pab-COOEt;EtOOCCH₂—(R)Cgl-Aze-Pab-COO-nBu;PrlC(O)CH₂CH₂CH₂OOCCH₂—(R)Cgl-Aze-Pab-Z;ChNHC(O)CH₂OOCCH₂—(R)Cgl-Aze-P-Z;(nPr)₂NC(O)CH₂OOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃;EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCC(CH₃)₃;EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH(CH₃)OOCCH₃; MeOOCCH₂—(R)Cgl-Aze-Pab-OOCPh;MeOOCCH₂—(R)Cgl-Aze-Pab-OH; EtOOCCH₂—(R)Cgl-Aze-Pab-OH;BnOOCCH₂—(R)Cgl-Aze-Pab-OH; nPrOOCCH₂—(R)Cgl-Aze-Pab-Z;nPrOOCCH₂—(R)Cgl-Aze-Pab-OH; iPrOOCCH₂—(R)Cgl-Aze-Pab-OH;tBuOOCCH₂—(R)Cgl-Aze-Pab-OH; (nPr)₂NCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-OH;ChNHCOCH₂OOCCH₂—(R)Cgl-Aze-Pab-OH; EtOOCCH₂—(R)Cgl-Aze-Pab-OAc;HOOCCH₂—(R)Cgl-Aze-Pab-OH; HOOCCH₂—(R)Cgl-Aze-Pab-O-cis-Oleyl;Cyclooctyl-OOCCH₂—(R)Cgl-Aze-Pab-Z; tBuCH₂OOCCH₂-(R)Cgl-Aze-Pab-Z;(2-Me)BnOOCCH₂-(R)Cgl-Aze-Pab-Z; ChCH₂OOCCH₂—(R)Cgl-Aze-Pab-Z;ChOOCCH₂—(R)Cgl-Aze-Pab-Z; PhC(Me)₂OOCCH₂—(R)Cgl-Aze-Pab-Z;(Me)₂CHC(Me)₂OOCCH₂—(R)Cgl-Aze-Pab-Z;BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe);ChCH₂OOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe);(2-Me)BnOOCCH₂—(R)Cgl-Aze-PabOOPh(4-OMe);EtOOCCH₂-(R)Cgl-Aze-Pab-COOPh(4-Me);BnOOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-Me); BnOOCCH₂—(R)Cgl-Aze-Pab-COO-nBu;iPrOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CH═CH₂; EtOOCCH₂—(R)Cgl-Aze-Pab-COO-iBu;BnOOCCH₂—(R)Cgl-Aze-Pab-COO-nPr; EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCCh;EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OCCH₂Ch;EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH(Me)OOCPh;EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCPh;BnOOCCH₂—(R)Cgl-Aze-Pab-COOCH(Me)OAc; EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OAc;tBuOOCCH₂-(R)Cgl-Aze-Pab-COOCH₂OAc;MeOOC—C(═CHEt)CH₂—OOCCH₂—(R)Cgl-Aze-Pab-Z;Men-OOCCH₂—(R)Cgl-Aze-Pab-COOPh(4-OMe); andEtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CCl₃.
 32. A compound as claimed in claim 1which is EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂CCl₃;BnOOCCH₂—(R)Cgl-Aze-Pab-COOnBu; nPrOOCCH₂—(R)Cgl-Aze-Pab-Z;Cyclooctyl-OOCCH₂—(R)Cgl-Aze-Pab-Z; EtOOCCH₂—(R)Cgl-Aze-Pab-COOCH₂OOCCh;MeOOCCH₂—(R)Cgl-Aze-Pab-OH; EtOOCCH₂—(R)Cgl-Aze-Pab-OH;nPrOOCCH₂—(R)Cgl-Aze-Pab-OH; iPrOOCCH₂—(R)Cgl-Aze-Pab-OH;BnOOCCH₂—(R)Cgl-Aze-Pab-OH; and EtOOCCH₂—(R)Cgl-Aze-Pab-OAc.
 33. Acompound of formula I, as defined in claim 1, with the additionalproviso that R¹ does not represent -A¹C(O)OR⁴.
 34. A compound of formulaI, as defined in claim 1, with the additional proviso that R⁴ and R⁵ donot independently represent H.
 35. A compound of formula I, as definedin claim 1, with the additional proviso R⁶ does not represent C₁₋₁₇alkyl, when R² represents OC(O)R⁶.
 36. A compound of formula I, asdefined in claim 1, wherein R¹ represents -A¹C(O)OR⁴.
 37. A compound offormula I, as defined in claim 1, wherein R⁴ and R⁵ independentlyrepresent H.
 38. A compound of formula I, as defined in claim 1, whereinR⁶ represents C₁₋₁₇ alkyl, when R² represents OC(O)R⁶.
 39. Apharmaceutical formulation including a compound of formula I as definedin any one of claims 1 to 38, or a pharmaceutically acceptable saltthereof, in admixture with a pharmaceutically acceptable adjuvant,diluent or carrier.
 40. A compound of formula I, as defined in any oneof claims 1 to 38, or a pharmaceutically acceptable salt thereof, foruse as a pharmaceutical.
 41. A compound of formula I as defined in anyone of claims 1 to 38, or a pharmaceutically acceptable salt thereof,for use in the treatment of a condition where inhibition of thrombin isrequired.
 42. A compound of formula I as defined in any one of claims 1to 38, or a pharmaceutically acceptable salt thereof, for use in thetreatment of thrombosis.
 43. A compound of formula I as defined in anyone of claims 1 to 38, or a pharmaceutically acceptable salt thereof,for use as an anticoagulant.
 44. The use of a compound of formula I asdefined in any one of claims 1 to 38, or a pharmaceutically acceptablesalt thereof as active ingredient in the manufacture of a medicament forthe treatment of a condition where inhibition of thrombin is required.45. The use as claimed in claim 44, wherein the condition is thrombosis.46. The use of a compound of formula I as defined in any one of claims 1to 38, or a pharmaceutically acceptable salt thereof, as activeingredient in the manufacture of an anticoagulant.
 47. A method oftreatment of a condition where inhibition of thrombin is required whichmethod comprises administration of a therapeutically effective amount ofa compound of formula I as defined in any one of claims 1 to 38, or apharmaceutically acceptable salt thereof, to a person suffering from, orsusceptible to, such a condition.
 48. A method as claimed in claim 47,wherein the condition is thrombosis.
 49. A method as claimed in claim47, wherein the condition is hypercoagulability in blood and tissues.50. The use of a compound of formula I, as defined in claim 1 butwithout the provisos, as a prodrug.
 51. A process for the preparation ofcompounds of formula I which comprises: (a) for compounds of formula Iin which R² represents OH, reaction of a corresponding compound offormula I, wherein R² represents OC(O)R⁶ and R⁶ is as defined in claim 1with an alkoxide base; (b) for compounds of formula I in which R²represents OH, reaction of a corresponding compound of formula I whereinR² represents C(O)OR⁷ and R⁷ is as defined in claim 1 withhydroxylamine, or an acid addition salt thereof; (c) reaction of acorresponding compound of formula II, H—(R)Cgl-Aze-Pab-R²   II  whereinR² is as defined in claim 1 with a compound of formula III,R¹O(O)C—CH₂-L¹   III  wherein L¹ represents a leaving group and R¹ is asdefined in claim 1; (d) for compounds of formula I in which R¹represents H and R² represents OH or C(O)OR⁷, reaction of acorresponding compound of formula I wherein R¹ represents C₁₋₁₀ alkyl orC₁₋₃ alkylphenyl, and R² represents OH or C(O)OR⁷, with a base; (e) forcompounds of formula I wherein R² represents OC(O)R⁶ and R⁶ is asdefined in claim 1, reaction of a corresponding compound of formula Iwherein R² represents OH, with a compound of formula IV, R⁶C(O)—O—C(O)R⁶  IV  or a compound of formula V, R⁶C(O)Hal   V  wherein Hal representsCl or Br and, in both cases, R⁶ is as defined in claim 1; (f) forcompounds of formula I in which R¹ represents H and R² representsOC(O)R⁶, and R⁶ is as defined in claim 1, reaction of a correspondingcompound of formula VI, P¹O(O)C—CH₂—(R)Cgl-Aze-Pab-R²   VI  wherein P¹represents an acid labile ester protecting group and R² representsOC(O)R⁶, wherein R⁶ is as defined in claim 1, with an acid; (g) forcompounds of formula I in which R¹ represents R³, R³ represents C₁₋₁₀alkyl or C₁₋₃ alkylphenyl, and R² represents OH or C(O)OR⁷, and R⁷ is asdefined in claim 1 by a transesterification of a corresponding compoundof formula VII, R^(1a)O(O)C—CH₂—(R)Cgl-Aze-Pab-R²   VII  wherein R^(1a)represents a C₁₋₁₀ alkyl or C₁₋₃ alkylphenyl group other than that beingformed, or an alternative labile alkyl substituent and R² is as definedin claim 1.